Guide to the Secure Configuration of Red Hat Enterprise Linux 7

with profile DISA STIG for Red Hat Enterprise Linux 7
This profile contains configuration checks that align to the DISA STIG for Red Hat Enterprise Linux V1R4. In addition to being applicable to RHEL7, DISA recognizes this configuration baseline as applicable to the operating system tier of Red Hat technologies that are based off RHEL7, such as: - Red Hat Enterprise Linux Server - Red Hat Enterprise Linux Workstation and Desktop - Red Hat Enterprise Linux for HPC - Red Hat Storage
This guide presents a catalog of security-relevant configuration settings for Red Hat Enterprise Linux 7. It is a rendering of content structured in the eXtensible Configuration Checklist Description Format (XCCDF) in order to support security automation. The SCAP content is is available in the scap-security-guide package which is developed at https://www.open-scap.org/security-policies/scap-security-guide.

Providing system administrators with such guidance informs them how to securely configure systems under their control in a variety of network roles. Policy makers and baseline creators can use this catalog of settings, with its associated references to higher-level security control catalogs, in order to assist them in security baseline creation. This guide is a catalog, not a checklist, and satisfaction of every item is not likely to be possible or sensible in many operational scenarios. However, the XCCDF format enables granular selection and adjustment of settings, and their association with OVAL and OCIL content provides an automated checking capability. Transformations of this document, and its associated automated checking content, are capable of providing baselines that meet a diverse set of policy objectives. Some example XCCDF Profiles, which are selections of items that form checklists and can be used as baselines, are available with this guide. They can be processed, in an automated fashion, with tools that support the Security Content Automation Protocol (SCAP). The DISA STIG, which provides required settings for US Department of Defense systems, is one example of a baseline created from this guidance.
Do not attempt to implement any of the settings in this guide without first testing them in a non-operational environment. The creators of this guidance assume no responsibility whatsoever for its use by other parties, and makes no guarantees, expressed or implied, about its quality, reliability, or any other characteristic.

Profile Information

Profile TitleDISA STIG for Red Hat Enterprise Linux 7
Profile IDxccdf_org.ssgproject.content_profile_stig-rhel7-disa

CPE Platforms

  • cpe:/o:redhat:enterprise_linux:7
  • cpe:/o:redhat:enterprise_linux:7::client
  • cpe:/o:redhat:enterprise_linux:7::computenode

Revision History

Current version: 0.1.43

  • draft (as of 2019-02-21)

Table of Contents

  1. Services
    1. Obsolete Services
    2. FTP Server
    3. SNMP Server
    4. Cron and At Daemons
    5. X Window System
    6. Mail Server Software
    7. System Security Services Daemon
    8. Network Time Protocol
    9. Base Services
    10. NFS and RPC
    11. SSH Server
  2. System Settings
    1. Installing and Maintaining Software
    2. Configure Syslog
    3. Network Configuration and Firewalls
    4. Set Boot Loader Password
    5. SELinux
    6. Account and Access Control
    7. System Accounting with auditd
    8. File Permissions and Masks

Checklist

Group   Guide to the Secure Configuration of Red Hat Enterprise Linux 7   Group contains 98 groups and 242 rules
Group   Services   Group contains 26 groups and 46 rules

[ref]   The best protection against vulnerable software is running less software. This section describes how to review the software which Red Hat Enterprise Linux 7 installs on a system and disable software which is not needed. It then enumerates the software packages installed on a default Red Hat Enterprise Linux 7 system and provides guidance about which ones can be safely disabled.

Red Hat Enterprise Linux 7 provides a convenient minimal install option that essentially installs the bare necessities for a functional system. When building Red Hat Enterprise Linux 7 systems, it is highly recommended to select the minimal packages and then build up the system from there.

Group   Obsolete Services   Group contains 4 groups and 7 rules

[ref]   This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or severely limiting the service has been the best available guidance for some time. As a result of this, many of these services are not installed as part of Red Hat Enterprise Linux 7 by default.

Organizations which are running these services should switch to more secure equivalents as soon as possible. If it remains absolutely necessary to run one of these services for legacy reasons, care should be taken to restrict the service as much as possible, for instance by configuring host firewall software such as firewalld to restrict access to the vulnerable service to only those remote hosts which have a known need to use it.

Group   Rlogin, Rsh, and Rexec   Group contains 3 rules

[ref]   The Berkeley r-commands are legacy services which allow cleartext remote access and have an insecure trust model.

Rule   Remove Host-Based Authentication Files   [ref]

The shosts.equiv file list remote hosts and users that are trusted by the local system. To remove these files, run the following command to delete them from any location:

$ sudo rm /[path]/[to]/[file]/shosts.equiv

Rationale:

The shosts.equiv files are used to configure host-based authentication for the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80513-5

References:  CCI-000366, SRG-OS-000480-GPOS-00227, RHEL-07-040550, SV-86903r2_rule

Remediation Shell script:   (show)


# Identify local mounts
MOUNT_LIST=$(df | grep "^/dev" | awk '{ print $6 }') 

# Find file on each listed mount point
for cur_mount in ${MOUNT_LIST}
do
	find ${cur_mount} -xdev -type f -name "shosts.equiv" -exec rm -f {} \;
done

Rule   Remove User Host-Based Authentication Files   [ref]

The ~/.shosts (in each user's home directory) files list remote hosts and users that are trusted by the local system. To remove these files, run the following command to delete them from any location:

$ sudo rm ~/.shosts

Rationale:

The .shosts files are used to configure host-based authentication for individual users or the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication.false

Severity: 
high
Identifiers and References

Identifiers:  CCE-80514-3

References:  CCI-000366, SRG-OS-000480-GPOS-00227, RHEL-07-040540, SV-86901r2_rule

Remediation Shell script:   (show)


# Identify local mounts
MOUNT_LIST=$(df | grep "^/dev" | awk '{ print $6 }') 

# Find file on each listed mount point
for cur_mount in ${MOUNT_LIST}
do
	find ${cur_mount} -xdev -type f -name ".shosts" -exec rm -f {} \;
done

Rule   Uninstall rsh-server Package   [ref]

The rsh-server package can be removed with the following command:

$ sudo yum erase rsh-server

Rationale:

The rsh-server service provides unencrypted remote access service which does not provide for the confidentiality and integrity of user passwords or the remote session and has very weak authentication. If a privileged user were to login using this service, the privileged user password could be compromised. The rsh-server package provides several obsolete and insecure network services. Removing it decreases the risk of those services' accidental (or intentional) activation.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27342-5

References:  RHEL-07-020000, SV-86591r2_rule, 11, 12, 14, 15, 3, 8, 9, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.05, DSS06.06, CCI-000381, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.2.1, A.6.2.2, A.9.1.2, AC-17(8), CM-7(a), PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000095-GPOS-00049

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:disable
# Function to remove packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_remove telnet-server
#
function package_remove {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_remove 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if rpm -q --quiet "$package"; then
    dnf remove -y "$package"
  fi
elif which yum ; then
  if rpm -q --quiet "$package"; then
    yum remove -y "$package"
  fi
elif which apt-get ; then
  apt-get remove -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_remove rsh-server
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure rsh-server is removed
  package:
    name: rsh-server
    state: absent
  tags:
    - package_rsh-server_removed
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27342-5
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7(a)
    - DISA-STIG-RHEL-07-020000
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_rsh-server

class remove_rsh-server {
  package { 'rsh-server':
    ensure => 'purged',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

package --remove=rsh-server
Group   Telnet   Group contains 1 rule

[ref]   The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication information such as passwords. Organizations which use telnet should be actively working to migrate to a more secure protocol.

Rule   Uninstall telnet-server Package   [ref]

The telnet-server package can be removed with the following command:

$ sudo yum erase telnet-server

Rationale:

It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities are often overlooked and therefore may remain unsecure. They increase the risk to the platform by providing additional attack vectors.
The telnet service provides an unencrypted remote access service which does not provide for the confidentiality and integrity of user passwords or the remote session. If a privileged user were to login using this service, the privileged user password could be compromised.
Removing the telnet-server package decreases the risk of the telnet service's accidental (or intentional) activation.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27165-0

References:  RHEL-07-021710, SV-86701r2_rule, 2.1.1, 11, 12, 14, 15, 3, 8, 9, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.05, DSS06.06, CCI-000381, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.2.1, A.6.2.2, A.9.1.2, AC-17(8), CM-7(a), PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000095-GPOS-00049

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:disable
# Function to remove packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_remove telnet-server
#
function package_remove {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_remove 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if rpm -q --quiet "$package"; then
    dnf remove -y "$package"
  fi
elif which yum ; then
  if rpm -q --quiet "$package"; then
    yum remove -y "$package"
  fi
elif which apt-get ; then
  apt-get remove -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_remove telnet-server
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure telnet-server is removed
  package:
    name: telnet-server
    state: absent
  tags:
    - package_telnet-server_removed
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27165-0
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7(a)
    - DISA-STIG-RHEL-07-021710
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_telnet-server

class remove_telnet-server {
  package { 'telnet-server':
    ensure => 'purged',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

package --remove=telnet-server
Group   NIS   Group contains 1 rule

[ref]   The Network Information Service (NIS), also known as 'Yellow Pages' (YP), and its successor NIS+ have been made obsolete by Kerberos, LDAP, and other modern centralized authentication services. NIS should not be used because it suffers from security problems inherent in its design, such as inadequate protection of important authentication information.

Rule   Uninstall ypserv Package   [ref]

The ypserv package can be removed with the following command:

$ sudo yum erase ypserv

Rationale:

The NIS service provides an unencrypted authentication service which does not provide for the confidentiality and integrity of user passwords or the remote session. Removing the ypserv package decreases the risk of the accidental (or intentional) activation of NIS or NIS+ services.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27399-5

References:  RHEL-07-020010, SV-86593r2_rule, 2.2.16, 11, 12, 14, 15, 3, 8, 9, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.05, DSS06.06, CCI-000381, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.2.1, A.6.2.2, A.9.1.2, AC-17(8), CM-7(a), PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000095-GPOS-00049

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:disable
# Function to remove packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_remove telnet-server
#
function package_remove {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_remove 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if rpm -q --quiet "$package"; then
    dnf remove -y "$package"
  fi
elif which yum ; then
  if rpm -q --quiet "$package"; then
    yum remove -y "$package"
  fi
elif which apt-get ; then
  apt-get remove -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_remove ypserv
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure ypserv is removed
  package:
    name: ypserv
    state: absent
  tags:
    - package_ypserv_removed
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27399-5
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7(a)
    - DISA-STIG-RHEL-07-020010
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_ypserv

class remove_ypserv {
  package { 'ypserv':
    ensure => 'purged',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

package --remove=ypserv
Group   TFTP Server   Group contains 2 rules

[ref]   TFTP is a lightweight version of the FTP protocol which has traditionally been used to configure networking equipment. However, TFTP provides little security, and modern versions of networking operating systems frequently support configuration via SSH or other more secure protocols. A TFTP server should be run only if no more secure method of supporting existing equipment can be found.

Rule   Uninstall tftp-server Package   [ref]

The tftp-server package can be removed with the following command:

 $ sudo yum erase tftp-server

Rationale:

Removing the tftp-server package decreases the risk of the accidental (or intentional) activation of tftp services.

If TFTP is required for operational support (such as transmission of router configurations), its use must be documented with the Information Systems Securty Manager (ISSM), restricted to only authorized personnel, and have access control rules established.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80213-2

References:  RHEL-07-040700, SV-86925r2_rule, 11, 12, 14, 15, 3, 8, 9, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.05, DSS06.06, CCI-000318, CCI-000368, CCI-001812, CCI-001813, CCI-001814, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.2.1, A.6.2.2, A.9.1.2, AC-17(8), CM-6(c), CM-7, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:disable
# Function to remove packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_remove telnet-server
#
function package_remove {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_remove 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if rpm -q --quiet "$package"; then
    dnf remove -y "$package"
  fi
elif which yum ; then
  if rpm -q --quiet "$package"; then
    yum remove -y "$package"
  fi
elif which apt-get ; then
  apt-get remove -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_remove tftp-server
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure tftp-server is removed
  package:
    name: tftp-server
    state: absent
  tags:
    - package_tftp-server_removed
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-80213-2
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-6(c)
    - NIST-800-53-CM-7
    - DISA-STIG-RHEL-07-040700
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_tftp-server

class remove_tftp-server {
  package { 'tftp-server':
    ensure => 'purged',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

package --remove=tftp-server

Rule   Ensure tftp Daemon Uses Secure Mode   [ref]

If running the tftp service is necessary, it should be configured to change its root directory at startup. To do so, ensure /etc/xinetd.d/tftp includes -s as a command line argument, as shown in the following example (which is also the default):

server_args = -s /var/lib/tftpboot

Rationale:

Using the -s option causes the TFTP service to only serve files from the given directory. Serving files from an intentionally-specified directory reduces the risk of sharing files which should remain private.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80214-0

References:  RHEL-07-040720, SV-86929r3_rule, 11, 12, 13, 14, 15, 16, 18, 3, 5, 8, 9, APO01.06, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06, CCI-000366, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.1.2, A.6.2.1, A.6.2.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, AC-17(8), CM-7, PR.AC-3, PR.AC-4, PR.DS-5, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000480-GPOS-00227

Group   FTP Server   Group contains 1 group and 1 rule

[ref]   FTP is a common method for allowing remote access to files. Like telnet, the FTP protocol is unencrypted, which means that passwords and other data transmitted during the session can be captured and that the session is vulnerable to hijacking. Therefore, running the FTP server software is not recommended.

However, there are some FTP server configurations which may be appropriate for some environments, particularly those which allow only read-only anonymous access as a means of downloading data available to the public.

Group   Disable vsftpd if Possible   Group contains 1 rule

[ref]   To minimize attack surface, disable vsftpd if at all possible.

Rule   Uninstall vsftpd Package   [ref]

The vsftpd package can be removed with the following command:

 $ sudo yum erase vsftpd

Rationale:

Removing the vsftpd package decreases the risk of its accidental activation.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80245-4

References:  RHEL-07-040690, SV-86923r3_rule, 11, 14, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.05, DSS06.06, CCI-000366, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.9.1.2, CM-6(b), CM-7, PR.IP-1, PR.PT-3, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:disable
# Function to remove packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_remove telnet-server
#
function package_remove {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_remove 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if rpm -q --quiet "$package"; then
    dnf remove -y "$package"
  fi
elif which yum ; then
  if rpm -q --quiet "$package"; then
    yum remove -y "$package"
  fi
elif which apt-get ; then
  apt-get remove -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_remove vsftpd
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure vsftpd is removed
  package:
    name: vsftpd
    state: absent
  tags:
    - package_vsftpd_removed
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-80245-4
    - NIST-800-53-CM-6(b)
    - NIST-800-53-CM-7
    - DISA-STIG-RHEL-07-040690
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_vsftpd

class remove_vsftpd {
  package { 'vsftpd':
    ensure => 'purged',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

package --remove=vsftpd
Group   SNMP Server   Group contains 1 group and 1 rule

[ref]   The Simple Network Management Protocol allows administrators to monitor the state of network devices, including computers. Older versions of SNMP were well-known for weak security, such as plaintext transmission of the community string (used for authentication) and usage of easily-guessable choices for the community string.

Group   Configure SNMP Server if Necessary   Group contains 1 rule

[ref]   If it is necessary to run the snmpd agent on the system, some best practices should be followed to minimize the security risk from the installation. The multiple security models implemented by SNMP cannot be fully covered here so only the following general configuration advice can be offered:

  • use only SNMP version 3 security models and enable the use of authentication and encryption
  • write access to the MIB (Management Information Base) should be allowed only if necessary
  • all access to the MIB should be restricted following a principle of least privilege
  • network access should be limited to the maximum extent possible including restricting to expected network addresses both in the configuration files and in the system firewall rules
  • ensure SNMP agents send traps only to, and accept SNMP queries only from, authorized management stations
  • ensure that permissions on the snmpd.conf configuration file (by default, in /etc/snmp) are 640 or more restrictive
  • ensure that any MIB files' permissions are also 640 or more restrictive

Rule   Ensure Default SNMP Password Is Not Used   [ref]

Edit /etc/snmp/snmpd.conf, remove or change the default community strings of public and private. Once the default community strings have been changed, restart the SNMP service:

$ sudo service snmpd restart

Rationale:

Whether active or not, default simple network management protocol (SNMP) community strings must be changed to maintain security. If the service is running with the default authenticators, then anyone can gather data about the system and the network and use the information to potentially compromise the integrity of the system and network(s).

Severity: 
high
Identifiers and References

Identifiers:  CCE-27386-2

References:  RHEL-07-040800, SV-86937r2_rule, 1, 12, 15, 16, 5, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10, CCI-000366, 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3, IA-5.1(ii), PR.AC-1, PR.AC-6, PR.AC-7, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)


if grep -s "public\|private" /etc/snmp/snmpd.conf | grep -qv "^#"; then
	sed -i "/^\s*#/b;/public\|private/ s/^/#/" /etc/snmp/snmpd.conf
fi
Group   Cron and At Daemons   Group contains 1 group and 2 rules

[ref]   The cron and at services are used to allow commands to be executed at a later time. The cron service is required by almost all systems to perform necessary maintenance tasks, while at may or may not be required on a given system. Both daemons should be configured defensively.

Group   Restrict at and cron to Authorized Users if Necessary   Group contains 2 rules

[ref]   The /etc/cron.allow and /etc/at.allow files contain lists of users who are allowed to use cron and at to delay execution of processes. If these files exist and if the corresponding files /etc/cron.deny and /etc/at.deny do not exist, then only users listed in the relevant allow files can run the crontab and at commands to submit jobs to be run at scheduled intervals. On many systems, only the system administrator needs the ability to schedule jobs. Note that even if a given user is not listed in cron.allow, cron jobs can still be run as that user. The cron.allow file controls only administrative access to the crontab command for scheduling and modifying cron jobs.

To restrict at and cron to only authorized users:

  • Remove the cron.deny file:
    $ sudo rm /etc/cron.deny
  • Edit /etc/cron.allow, adding one line for each user allowed to use the crontab command to create cron jobs.
  • Remove the at.deny file:
    $ sudo rm /etc/at.deny
  • Edit /etc/at.allow, adding one line for each user allowed to use the at command to create at jobs.

Rule   Verify Group Who Owns /etc/cron.allow file   [ref]

If /etc/cron.allow exists, it must be group-owned by root. To properly set the group owner of /etc/cron.allow, run the command:

$ sudo chgrp root /etc/cron.allow

Rationale:

If the owner of the cron.allow file is not set to root, the possibility exists for an unauthorized user to view or edit sensitive information.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80379-1

References:  RHEL-07-021120, SV-86679r2_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, CCI-000366, 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure

chgrp 0 /etc/cron.allow
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Test for existence /etc/cron.allow
  stat:
    path: /etc/cron.allow
  register: file_exists

- name: Ensure group owner 0 on /etc/cron.allow
  file:
    path: /etc/cron.allow
    group: 0
  when: file_exists.stat.exists and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - file_groupowner_cron_allow
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-80379-1
    - NIST-800-53-AC-6
    - DISA-STIG-RHEL-07-021120

Rule   Verify User Who Owns /etc/cron.allow file   [ref]

If /etc/cron.allow exists, it must be owned by root. To properly set the owner of /etc/cron.allow, run the command:

$ sudo chown root /etc/cron.allow 

Rationale:

If the owner of the cron.allow file is not set to root, the possibility exists for an unauthorized user to view or edit sensitive information.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80378-3

References:  RHEL-07-021110, SV-86677r3_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, CCI-000366, 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure

chown 0 /etc/cron.allow
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Test for existence /etc/cron.allow
  stat:
    path: /etc/cron.allow
  register: file_exists

- name: Ensure owner 0 on /etc/cron.allow
  file:
    path: /etc/cron.allow
    owner: 0
  when: file_exists.stat.exists and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - file_owner_cron_allow
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-80378-3
    - NIST-800-53-AC-6
    - DISA-STIG-RHEL-07-021110
Group   X Window System   Group contains 1 group and 1 rule

[ref]   The X Window System implementation included with the system is called X.org.

Group   Disable X Windows   Group contains 1 rule

[ref]   Unless there is a mission-critical reason for the system to run a graphical user interface, ensure X is not set to start automatically at boot and remove the X Windows software packages. There is usually no reason to run X Windows on a dedicated server system, as it increases the system's attack surface and consumes system resources. Administrators of server systems should instead login via SSH or on the text console.

Rule   Remove the X Windows Package Group   [ref]

By removing the xorg-x11-server-common package, the system no longer has X Windows installed. If X Windows is not installed then the system cannot boot into graphical user mode. This prevents the system from being accidentally or maliciously booted into a graphical.target mode. To do so, run the following command:

$ sudo yum groupremove "X Window System"
$ sudo yum remove xorg-x11-server-common

Rationale:

Unnecessary service packages must not be installed to decrease the attack surface of the system. X windows has a long history of security vulnerabilities and should not be installed unless approved and documented.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27218-7

References:  RHEL-07-040730, SV-86931r4_rule, 2.2.2, 12, 15, 8, APO13.01, DSS01.04, DSS05.02, DSS05.03, CCI-000366, 4.3.3.6.6, SR 1.13, SR 2.6, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.13.1.1, A.13.2.1, A.14.1.3, A.6.2.1, A.6.2.2, AC-17(8).1(ii), PR.AC-3, PR.PT-4, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:disable
# Function to remove packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_remove telnet-server
#
function package_remove {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_remove 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if rpm -q --quiet "$package"; then
    dnf remove -y "$package"
  fi
elif which yum ; then
  if rpm -q --quiet "$package"; then
    yum remove -y "$package"
  fi
elif which apt-get ; then
  apt-get remove -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_remove xorg-x11-server-common
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure xorg-x11-server-common is removed
  package:
    name: xorg-x11-server-common
    state: absent
  tags:
    - package_xorg-x11-server-common_removed
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27218-7
    - NIST-800-53-AC-17(8).1(ii)
    - DISA-STIG-RHEL-07-040730
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_xorg-x11-server-common

class remove_xorg-x11-server-common {
  package { 'xorg-x11-server-common':
    ensure => 'purged',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

package --remove=xorg-x11-server-common
Group   Mail Server Software   Group contains 3 groups and 1 rule

[ref]   Mail servers are used to send and receive email over the network. Mail is a very common service, and Mail Transfer Agents (MTAs) are obvious targets of network attack. Ensure that systems are not running MTAs unnecessarily, and configure needed MTAs as defensively as possible.

Very few systems at any site should be configured to directly receive email over the network. Users should instead use mail client programs to retrieve email from a central server that supports protocols such as IMAP or POP3. However, it is normal for most systems to be independently capable of sending email, for instance so that cron jobs can report output to an administrator. Most MTAs, including Postfix, support a submission-only mode in which mail can be sent from the local system to a central site MTA (or directly delivered to a local account), but the system still cannot receive mail directly over a network.

The alternatives program in Red Hat Enterprise Linux 7 permits selection of other mail server software (such as Sendmail), but Postfix is the default and is preferred. Postfix was coded with security in mind and can also be more effectively contained by SELinux as its modular design has resulted in separate processes performing specific actions. More information is available on its website, http://www.postfix.org.

Group   Configure Operating System to Protect Mail Server   Group contains 2 groups and 1 rule

[ref]   The guidance in this section is appropriate for any host which is operating as a site MTA, whether the mail server runs using Sendmail, Postfix, or some other software.

Group   Configure Postfix if Necessary   Group contains 1 group and 1 rule

[ref]   Postfix stores its configuration files in the directory /etc/postfix by default. The primary configuration file is /etc/postfix/main.cf.

Group   Control Mail Relaying   Group contains 1 rule

[ref]   Postfix's mail relay controls are implemented with the help of the smtpd recipient restrictions option, which controls the restrictions placed on the SMTP dialogue once the sender and recipient envelope addresses are known. The guidance in the following sections should be applied to all systems. If there are systems which must be allowed to relay mail, but which cannot be trusted to relay unconditionally, configure SMTP AUTH with SSL support.

Rule   Prevent Unrestricted Mail Relaying   [ref]

Modify the

/etc/postfix/main.cf
file to restrict client connections to the local network with the following command:
$ sudo postconf -e 'smtpd_client_restrictions = permit_mynetworks,reject'

Rationale:

If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay for the purpose of sending spam or other unauthorized activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80512-7

References:  CCI-000366, SRG-OS-000480-GPOS-00227, RHEL-07-040680, SV-86921r3_rule

Remediation Shell script:   (show)


if ! grep -q ^smtpd_client_restrictions /etc/postfix/main.cf; then
	echo "smtpd_client_restrictions = permit_mynetworks,reject" >> /etc/postfix/main.cf
else
	sed -i "s/^smtpd_client_restrictions.*/smtpd_client_restrictions = permit_mynetworks,reject/g" /etc/postfix/main.cf
fi
Group   System Security Services Daemon   Group contains 1 group and 4 rules

[ref]   The System Security Services Daemon (SSSD) is a system daemon that provides access to different identity and authentication providers such as Red Hat's IdM, Microsoft's AD, openLDAP, MIT Kerberos, etc. It uses a common framework that can provide caching and offline support to systems utilizing SSSD. SSSD using caching to reduce load on authentication servers permit offline authentication as well as store extended user data.

For more information, see https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System-Level_Authentication_Guide/SSSD.html

Group   System Security Services Daemon (SSSD) - LDAP   Group contains 3 rules

[ref]   The System Security Services Daemon (SSSD) is a system daemon that provides access to different identity and authentication providers such as Red Hat's IdM, Microsoft's AD, openLDAP, MIT Kerberos, etc. It uses a common framework that can provide caching and offline support to systems utilizing SSSD. SSSD using caching to reduce load on authentication servers permit offline authentication as well as store extended user data.

SSSD can support many backends including LDAP. The sssd-ldap backend allows SSSD to fetch identity information from an LDAP server.

Rule   Configure SSSD LDAP Backend Client CA Certificate Location   [ref]

Configure SSSD to implement cryptography to protect the integrity of LDAP remote access sessions. By setting the

ldap_tls_cacertdir
option in
/etc/sssd/sssd.conf
to point to the path for the X.509 certificates used for peer authentication.
ldap_tls_cacertdir /path/to/tls/cacert

Rationale:

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the key used to generate the hash.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80515-0

References:  CCI-001453, SRG-OS-000250-GPOS-00093, RHEL-07-040190, SV-86853r3_rule

Remediation Shell script:   (show)


var_sssd_ldap_tls_ca_dir="/etc/openldap/cacerts"

SSSD_CONF="/etc/sssd/sssd.conf"
LDAP_REGEX='[[:space:]]*\[domain\/[^]]*]([^(\n)]*(\n)+)+?[[:space:]]*ldap_tls_cacertdir'
DOMAIN_REGEX="[[:space:]]*\[domain\/[^]]*]"

# Try find [domain/..] and ldap_tls_cacertdir in sssd.conf, if it exists, set to CA directory
# if it isn't here, add it, if [domain/..] doesn't exist, add it here for default domain
if grep -qzosP $LDAP_REGEX $SSSD_CONF; then
        sed -i "s~ldap_tls_cacertdir[^(\n)]*~ldap_tls_cacertdir = $var_sssd_ldap_tls_ca_dir~" $SSSD_CONF
elif grep -qs $DOMAIN_REGEX $SSSD_CONF; then
        sed -i "/$DOMAIN_REGEX/a ldap_tls_cacertdir = $var_sssd_ldap_tls_ca_dir" $SSSD_CONF
else
        mkdir -p /etc/sssd
        touch $SSSD_CONF
        echo -e "[domain/default]\nldap_tls_cacertdir = $var_sssd_ldap_tls_ca_dir" >> $SSSD_CONF
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: XCCDF Value var_sssd_ldap_tls_ca_dir # promote to variable
  set_fact:
    var_sssd_ldap_tls_ca_dir: !!str /etc/openldap/cacerts
  tags:
    - always

- name: "Test for domain group"
  shell: grep '\s*\[domain\/[^]]*]' /etc/sssd/sssd.conf
  register: test_grep_domain
  ignore_errors: yes
  tags:
    - sssd_ldap_configure_tls_ca_dir
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80515-0
    - DISA-STIG-RHEL-07-040190
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Add default domain group and set CA directory (if no domain there)"
  lineinfile:
    path: /etc/sssd/sssd.conf
    create: yes
    line: "[domain/default]\nldap_tls_cacertdir = {{ var_sssd_ldap_tls_ca_dir }}\n"
  when: test_grep_domain.stdout == "" and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - sssd_ldap_configure_tls_ca_dir
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80515-0
    - DISA-STIG-RHEL-07-040190

- name: "Configure LDAPs path to CA directory"
  lineinfile:
    path: /etc/sssd/sssd.conf
    regexp: '^\s*ldap_tls_cacertdir'
    insertafter: '\s*\[domain\/[^]]*]'
    line: 'ldap_tls_cacertdir = {{ var_sssd_ldap_tls_ca_dir }}'
  tags:
    - sssd_ldap_configure_tls_ca_dir
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80515-0
    - DISA-STIG-RHEL-07-040190
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Configure SSSD LDAP Backend to Use TLS For All Transactions   [ref]

This check verifies that Red Hat Enterprise Linux 7 implements cryptography to protect the integrity of remote LDAP authentication sessions.

To determine if LDAP is being used for authentication, use the following command:

$ sudo grep -i useldapauth /etc/sysconfig/authconfig


If USELDAPAUTH=yes, then LDAP is being used. To check if LDAP is configured to use TLS, use the following command:
$ sudo grep -i ldap_id_use_start_tls /etc/sssd/sssd.conf

Rationale:

Without cryptographic integrity protections, information can be altered by unauthorized users without detection. The ssl directive specifies whether to use TLS or not. If not specified it will default to no. It should be set to start_tls rather than doing LDAP over SSL.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80546-5

References:  RHEL-07-040180, SV-86851r3_rule, 11, 12, 14, 15, 3, 8, 9, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.05, DSS06.06, CCI-001453, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.2.1, A.6.2.2, A.9.1.2, AC-17(2), CM-7, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000250-GPOS-00093

Remediation Shell script:   (show)



AUTHCONFIG="/etc/sysconfig/authconfig"
USELDAPAUTH_REGEX="^USELDAPAUTH="
SSSD_CONF="/etc/sssd/sssd.conf"
LDAP_REGEX='[[:space:]]*\[domain\/[^]]*]([^(\n)]*(\n)+)+?[[:space:]]*ldap_id_use_start_tls'
DOMAIN_REGEX="[[:space:]]*\[domain\/[^]]*]"

# Try find USELDAPAUTH in authconfig. If its here set to 'yes', otherwise append USELDAPAUTH=yes
grep -qs "^USELDAPAUTH=" "$AUTHCONFIG" && sed -i 's/^USELDAPAUTH=.*/USELDAPAUTH=yes/g' $AUTHCONFIG
if ! [ $? -eq 0 ]; then
        echo "USELDAPAUTH=yes" >> $AUTHCONFIG
fi

# Try find [domain/..] and ldap_id_use_start_tls in sssd.conf, if it exists, set to 'True'
# if ldap_id_use_start_tls isn't here, add it
# if [domain/..] doesn't exist, add it here for default domain
if grep -qzosP $LDAP_REGEX $SSSD_CONF; then
        sed -i 's/ldap_id_use_start_tls[^(\n)]*/ldap_id_use_start_tls = True/' $SSSD_CONF
elif grep -qs $DOMAIN_REGEX $SSSD_CONF; then
        sed -i "/$DOMAIN_REGEX/a ldap_id_use_start_tls = True" $SSSD_CONF
else
        mkdir -p /etc/sssd
        touch $SSSD_CONF
        echo -e "[domain/default]\nldap_id_use_start_tls = True" >> $SSSD_CONF
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium

- name: "Set LDAP to be used for authentication"
  lineinfile:
    path: /etc/sysconfig/authconfig
    regexp: '^USELDAPAUTH='
    line: 'USELDAPAUTH=yes'
    create: yes
  tags:
    - sssd_ldap_start_tls
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80546-5
    - NIST-800-53-AC-17(2)
    - NIST-800-53-CM-7
    - DISA-STIG-RHEL-07-040180
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Test for domain group"
  shell: grep '\s*\[domain\/[^]]*]' /etc/sssd/sssd.conf
  register: test_grep_domain
  ignore_errors: yes
  tags:
    - sssd_ldap_start_tls
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80546-5
    - NIST-800-53-AC-17(2)
    - NIST-800-53-CM-7
    - DISA-STIG-RHEL-07-040180
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Add default domain group and use STARTTLS (if no domain there)"
  lineinfile:
    path: /etc/sssd/sssd.conf
    line: "[domain/default]\nldap_id_use_start_tls = True\n"
  when: test_grep_domain.stdout == "" and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - sssd_ldap_start_tls
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80546-5
    - NIST-800-53-AC-17(2)
    - NIST-800-53-CM-7
    - DISA-STIG-RHEL-07-040180

- name: "Configure LDAP to use STARTTLS"
  lineinfile:
    path: /etc/sssd/sssd.conf
    regexp: '^\s*ldap_id_use_start_tls'
    insertafter: '\s*\[domain\/[^]]*]'
    line: 'ldap_id_use_start_tls = True'
  tags:
    - sssd_ldap_start_tls
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80546-5
    - NIST-800-53-AC-17(2)
    - NIST-800-53-CM-7
    - DISA-STIG-RHEL-07-040180
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Configure SSSD LDAP Backend Client CA Certificate   [ref]

Configure SSSD to implement cryptography to protect the integrity of LDAP remote access sessions. By setting the

ldap_tls_cacert
option in
/etc/sssd/sssd.conf
to point to the path for the X.509 certificates used for peer authentication.
ldap_tls_cacert /path/to/tls/ca.cert

Rationale:

Without cryptographic integrity protections, information can be altered by unauthorized users without detection.

Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the key used to generate the hash.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80516-8

References:  CCI-001453, SRG-OS-000250-GPOS-00093, RHEL-07-040200, SV-86855r3_rule

Rule   Configure PAM in SSSD Services   [ref]

SSSD should be configured to run SSSD pam services. To configure SSSD to known SSH hosts, add pam to services under the [sssd] section in /etc/sssd/sssd.conf. For example:

[sssd]
services = sudo, autofs, pam

Rationale:

Using an authentication device, such as a CAC or token that is separate from the information system, ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80437-7

References:  RHEL-07-041002, SV-87051r4_rule, 1, 12, 15, 16, 5, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10, CCI-001948, CCI-001953, CCI-001954, 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, A.18.1.4, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3, IA-2(11), PR.AC-1, PR.AC-6, PR.AC-7, SRG-OS-000375-GPOS-00160, SRG-OS-000375-GPOS-00161, SRG-OS-000375-GPOS-00162, SRG-OS-000107-VMM-000530

Remediation Shell script:   (show)



SSSD_SERVICES_PAM_REGEX="^[[:space:]]*\[sssd]([^\n]*\n+)+?[[:space:]]*services.*pam.*$"
SSSD_SERVICES_REGEX="^[[:space:]]*\[sssd]([^\n]*\n+)+?[[:space:]]*services.*$"
SSSD_PAM_SERVICES="[sssd]
services = pam"
SSSD_CONF="/etc/sssd/sssd.conf"

# If there is services line with pam, good
# If there is services line without pam, append pam
# If not echo services line with pam
grep -q "$SSSD_SERVICES_PAM_REGEX" $SSSD_CONF || \
	grep -q "$SSSD_SERVICES_REGEX" $SSSD_CONF && \
	sed -i "s/$SSSD_SERVICES_REGEX/&, pam/" $SSSD_CONF || \
	echo "$SSSD_PAM_SERVICES" >> $SSSD_CONF
Group   Network Time Protocol   Group contains 1 rule

[ref]   The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictably on unmanaged systems. Central time protocols can be used both to ensure that time is consistent among a network of systems, and that their time is consistent with the outside world.

If every system on a network reliably reports the same time, then it is much easier to correlate log messages in case of an attack. In addition, a number of cryptographic protocols (such as Kerberos) use timestamps to prevent certain types of attacks. If your network does not have synchronized time, these protocols may be unreliable or even unusable.

Depending on the specifics of the network, global time accuracy may be just as important as local synchronization, or not very important at all. If your network is connected to the Internet, using a public timeserver (or one provided by your enterprise) provides globally accurate timestamps which may be essential in investigating or responding to an attack which originated outside of your network.

A typical network setup involves a small number of internal systems operating as NTP servers, and the remainder obtaining time information from those internal servers.

There is a choice between the daemons ntpd and chronyd, which are available from the repositories in the ntp and chrony packages respectively.

The default chronyd daemon can work well when external time references are only intermittently accesible, can perform well even when the network is congested for longer periods of time, can usually synchronize the clock faster and with better time accuracy, and quickly adapts to sudden changes in the rate of the clock, for example, due to changes in the temperature of the crystal oscillator. Chronyd should be considered for all systems which are frequently suspended or otherwise intermittently disconnected and reconnected to a network. Mobile and virtual systems for example.

The ntpd NTP daemon fully supports NTP protocol version 4 (RFC 5905), including broadcast, multicast, manycast clients and servers, and the orphan mode. It also supports extra authentication schemes based on public-key cryptography (RFC 5906). The NTP daemon (ntpd) should be considered for systems which are normally kept permanently on. Systems which are required to use broadcast or multicast IP, or to perform authentication of packets with the Autokey protocol, should consider using ntpd.

Refer to https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/ch-Configuring_NTP_Using_the_chrony_Suite.html for more detailed comparison of features of chronyd and ntpd daemon features respectively, and for further guidance how to choose between the two NTP daemons.

The upstream manual pages at http://chrony.tuxfamily.org/manual.html for chronyd and http://www.ntp.org for ntpd provide additional information on the capabilities and configuration of each of the NTP daemons.

Rule   Configure Time Service Maxpoll Interval   [ref]

The maxpoll should be configured to 10 in /etc/ntp.conf or /etc/chrony.conf to continuously poll time servers. To configure maxpoll in /etc/ntp.conf or /etc/chrony.conf add the following:

maxpoll 10

Rationale:

Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate.

Severity: 
unknown
Identifiers and References

Identifiers:  CCE-80439-3

References:  RHEL-07-040500, SV-86893r4_rule, 1, 14, 15, 16, 3, 5, 6, APO11.04, BAI03.05, DSS05.04, DSS05.07, MEA02.01, CCI-001891, CCI-002046, 4.3.3.3.9, 4.3.3.5.8, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 2.10, SR 2.11, SR 2.12, SR 2.8, SR 2.9, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, AU-8(1)(a), PR.PT-1, SRG-OS-000355-GPOS-00143, SRG-OS-000356-GPOS-00144

Remediation Shell script:   (show)


var_time_service_set_maxpoll="10"


config_file="/etc/ntp.conf"
/usr/sbin/pidof ntpd || config_file="/etc/chrony.conf"


# Set maxpoll values to var_time_service_set_maxpoll
sed -i "s/^\(server.*maxpoll\) [0-9][0-9]*\(.*\)$/\1 $var_time_service_set_maxpoll \2/" "$config_file"

# Add maxpoll to server entries without maxpoll
grep "^server" "$config_file" | grep -v maxpoll | while read -r line ; do
        sed -i "s/$line/& maxpoll $var_time_service_set_maxpoll/" "$config_file"
done
Group   Base Services   Group contains 1 rule

[ref]   This section addresses the base services that are installed on a Red Hat Enterprise Linux 7 default installation which are not covered in other sections. Some of these services listen on the network and should be treated with particular discretion. Other services are local system utilities that may or may not be extraneous. In general, system services should be disabled if not required.

Rule   Disable KDump Kernel Crash Analyzer (kdump)   [ref]

The kdump service provides a kernel crash dump analyzer. It uses the kexec system call to boot a secondary kernel ("capture" kernel) following a system crash, which can load information from the crashed kernel for analysis. The kdump service can be disabled with the following command:

$ sudo systemctl disable kdump.service

Rationale:

Kernel core dumps may contain the full contents of system memory at the time of the crash. Kernel core dumps consume a considerable amount of disk space and may result in denial of service by exhausting the available space on the target file system partition. Unless the system is used for kernel development or testing, there is little need to run the kdump service.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80258-7

References:  RHEL-07-021300, SV-86681r2_rule, 11, 12, 14, 15, 3, 8, 9, APO13.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.05, DSS06.06, CCI-000366, 164.308(a)(1)(ii)(D), 164.308(a)(3), 164.308(a)(4), 164.310(b), 164.310(c), 164.312(a), 164.312(e), 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.2.1, A.6.2.2, A.9.1.2, AC-17(8), CM-7, CM-6(b), PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'kdump.service'
"$SYSTEMCTL_EXEC" disable 'kdump.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^kdump.socket\>' && "$SYSTEMCTL_EXEC" disable 'kdump.socket'
# The service may not be running because it has been started and failed,
# so let's reset the state so OVAL checks pass.
# Service should be 'inactive', not 'failed' after reboot though.
"$SYSTEMCTL_EXEC" reset-failed 'kdump.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service kdump
  service:
    name: kdump
    enabled: "no"
    state: "stopped"
  register: service_result
  failed_when: "service_result is failed and ('Could not find the requested service' not in service_result.msg)"
  tags:
    - service_kdump_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-80258-7
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-CM-6(b)
    - DISA-STIG-RHEL-07-021300
  


- name: Disable socket of service kdump if applicable
  service:
    name: kdump.socket
    enabled: "no"
    state: "stopped"
  register: socket_result
  failed_when: "socket_result is failed and ('Could not find the requested service' not in socket_result.msg)"
  tags:
    - service_kdump_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-80258-7
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-CM-6(b)
    - DISA-STIG-RHEL-07-021300
  
Remediation Anaconda snippet:   (show)


kdump --disable
Group   NFS and RPC   Group contains 2 groups and 3 rules

[ref]   The Network File System is a popular distributed filesystem for the Unix environment, and is very widely deployed. This section discusses the circumstances under which it is possible to disable NFS and its dependencies, and then details steps which should be taken to secure NFS's configuration. This section is relevant to systems operating as NFS clients, as well as to those operating as NFS servers.

Group   Configure NFS Clients   Group contains 1 group and 3 rules

[ref]   The steps in this section are appropriate for systems which operate as NFS clients.

Group   Mount Remote Filesystems with Restrictive Options   Group contains 3 rules

[ref]   Edit the file /etc/fstab. For each filesystem whose type (column 3) is nfs or nfs4, add the text ,nodev,nosuid to the list of mount options in column 4. If appropriate, also add ,noexec.

See the section titled "Restrict Partition Mount Options" for a description of the effects of these options. In general, execution of files mounted via NFS should be considered risky because of the possibility that an adversary could intercept the request and substitute a malicious file. Allowing setuid files to be executed from remote servers is particularly risky, both for this reason and because it requires the clients to extend root-level trust to the NFS server.

Rule   Mount Remote Filesystems with Kerberos Security   [ref]

Add the sec=krb5:krb5i:krb5p option to the fourth column of /etc/fstab for the line which controls mounting of any NFS mounts.

Rationale:

When an NFS server is configured to use AUTH_SYS a selected userid and groupid are used to handle requests from the remote user. The userid and groupid could mistakenly or maliciously be set incorrectly. The AUTH_GSS method of authentication uses certificates on the server and client systems to more securely authenticate the remote mount request.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27458-9

References:  RHEL-07-040750, SV-86935r4_rule, 1, 12, 14, 15, 16, 18, 3, 5, DSS05.04, DSS05.10, DSS06.10, CCI-000366, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.3, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, A.18.1.4, A.6.1.2, A.9.1.2, A.9.2.1, A.9.2.3, A.9.2.4, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5, AC-14(1), PR.AC-4, PR.AC-7, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

function include_mount_options_functions {
	:
}

# $1: type of filesystem
# $2: new mount point option
function ensure_mount_option_for_vfstype {
        local _vfstype="$1" _new_opt="$2" _vfstype_points=()
        _vfstype_points=($(grep -E "[[:space:]]$_vfstype[[:space:]]" /etc/fstab | awk '{print $2}'))

        for _vfstype_point in "${_vfstype_points[@]}"
        do
                ensure_mount_option_in_fstab "$_vfstype_point" "$_new_opt"
        done
}

# $1: mount point
# $2: new mount point option
function ensure_mount_option_in_fstab {
	local _mount_point="$1" _new_opt="$2" _mount_point_match_regexp="" _previous_mount_opts=""
	_mount_point_match_regexp="$(get_mount_point_regexp "$_mount_point")"

	if [ $(grep "$_mount_point_match_regexp" /etc/fstab | grep -c "$_new_opt" ) -eq 0 ]; then
		_previous_mount_opts=$(grep "$_mount_point_match_regexp" /etc/fstab | awk '{print $4}')
		sed -i "s|\(${_mount_point_match_regexp}.*${_previous_mount_opts}\)|\1,${_new_opt}|" /etc/fstab
	fi
}

# $1: mount point
function get_mount_point_regexp {
		printf "[[:space:]]%s[[:space:]]" "$1"
}

# $1: mount point
function assert_mount_point_in_fstab {
	local _mount_point_match_regexp
	_mount_point_match_regexp="$(get_mount_point_regexp "$1")"
	grep "$_mount_point_match_regexp" -q /etc/fstab \
		|| { echo "The mount point '$1' is not even in /etc/fstab, so we can't set up mount options" >&2; return 1; }
}

# $1: mount point
function remove_defaults_from_fstab_if_overriden {
	local _mount_point_match_regexp
	_mount_point_match_regexp="$(get_mount_point_regexp "$1")"
	if $(grep "$_mount_point_match_regexp" /etc/fstab | grep -q "defaults,")
	then
		sed -i "s|\(${_mount_point_match_regexp}.*\)defaults,|\1|" /etc/fstab
	fi
}

# $1: mount point
function ensure_partition_is_mounted {
	local _mount_point="$1"
	mkdir -p "$_mount_point" || return 1
	if mountpoint -q "$_mount_point"; then
		mount -o remount --target "$_mount_point"
	else
		mount --target "$_mount_point"
	fi
}

include_mount_options_functions

ensure_mount_option_for_vfstype "nfs[4]?" "sec=krb5:krb5i:krb5p"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Strategy:configure

- name: "Get nfs and nfs4 mount points, that don't have Kerberos security option"
  shell: grep -E "[[:space:]]nfs[4]?[[:space:]]" /etc/fstab | grep -v "sec=krb5:krb5i:krb5p" | awk '{print $2}'
  register: points_register
  check_mode: no
  changed_when: False
  tags:
    - mount_option_krb_sec_remote_filesystems
    - medium_severity
    - configure_strategy
    - low_complexity
    - medium_disruption
    - CCE-27458-9
    - NIST-800-53-AC-14(1)
    - DISA-STIG-RHEL-07-040750
  

- name: "Add Kerberos security to mount points"
  shell: awk '$2=="{{ item }}"{$4=$4",sec=krb5:krb5i:krb5p"}1' /etc/fstab > fstab.tmp && mv fstab.tmp /etc/fstab
  with_items:
    - "{{ points_register.stdout_lines }}"
  when: (points_register.stdout | length > 0) and True
  tags:
    - mount_option_krb_sec_remote_filesystems
    - medium_severity
    - configure_strategy
    - low_complexity
    - medium_disruption
    - CCE-27458-9
    - NIST-800-53-AC-14(1)
    - DISA-STIG-RHEL-07-040750

Rule   Mount Remote Filesystems with noexec   [ref]

Add the noexec option to the fourth column of /etc/fstab for the line which controls mounting of any NFS mounts.

Rationale:

The noexec mount option causes the system not to execute binary files. This option must be used for mounting any file system not containing approved binary files as they may be incompatible. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80436-9

References:  RHEL-07-021021, SV-87813r2_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, CCI-000366, 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

function include_mount_options_functions {
	:
}

# $1: type of filesystem
# $2: new mount point option
function ensure_mount_option_for_vfstype {
        local _vfstype="$1" _new_opt="$2" _vfstype_points=()
        _vfstype_points=($(grep -E "[[:space:]]$_vfstype[[:space:]]" /etc/fstab | awk '{print $2}'))

        for _vfstype_point in "${_vfstype_points[@]}"
        do
                ensure_mount_option_in_fstab "$_vfstype_point" "$_new_opt"
        done
}

# $1: mount point
# $2: new mount point option
function ensure_mount_option_in_fstab {
	local _mount_point="$1" _new_opt="$2" _mount_point_match_regexp="" _previous_mount_opts=""
	_mount_point_match_regexp="$(get_mount_point_regexp "$_mount_point")"

	if [ $(grep "$_mount_point_match_regexp" /etc/fstab | grep -c "$_new_opt" ) -eq 0 ]; then
		_previous_mount_opts=$(grep "$_mount_point_match_regexp" /etc/fstab | awk '{print $4}')
		sed -i "s|\(${_mount_point_match_regexp}.*${_previous_mount_opts}\)|\1,${_new_opt}|" /etc/fstab
	fi
}

# $1: mount point
function get_mount_point_regexp {
		printf "[[:space:]]%s[[:space:]]" "$1"
}

# $1: mount point
function assert_mount_point_in_fstab {
	local _mount_point_match_regexp
	_mount_point_match_regexp="$(get_mount_point_regexp "$1")"
	grep "$_mount_point_match_regexp" -q /etc/fstab \
		|| { echo "The mount point '$1' is not even in /etc/fstab, so we can't set up mount options" >&2; return 1; }
}

# $1: mount point
function remove_defaults_from_fstab_if_overriden {
	local _mount_point_match_regexp
	_mount_point_match_regexp="$(get_mount_point_regexp "$1")"
	if $(grep "$_mount_point_match_regexp" /etc/fstab | grep -q "defaults,")
	then
		sed -i "s|\(${_mount_point_match_regexp}.*\)defaults,|\1|" /etc/fstab
	fi
}

# $1: mount point
function ensure_partition_is_mounted {
	local _mount_point="$1"
	mkdir -p "$_mount_point" || return 1
	if mountpoint -q "$_mount_point"; then
		mount -o remount --target "$_mount_point"
	else
		mount --target "$_mount_point"
	fi
}

include_mount_options_functions

ensure_mount_option_for_vfstype "nfs[4]?" "noexec"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Strategy:configure

- name: "Get nfs and nfs4 mount points, that don't have noexec"
  shell: grep -E "[[:space:]]nfs[4]?[[:space:]]" /etc/fstab | grep -v "noexec" | awk '{print $2}'
  register: points_register
  check_mode: no
  changed_when: False
  tags:
    - mount_option_noexec_remote_filesystems
    - medium_severity
    - configure_strategy
    - low_complexity
    - medium_disruption
    - CCE-80436-9
    - NIST-800-53-AC-6
    - DISA-STIG-RHEL-07-021021
  

- name: "Add noexec to mount points"
  shell: awk '$2=="{{ item }}"{$4=$4",noexec"}1' /etc/fstab > fstab.tmp && mv fstab.tmp /etc/fstab
  with_items:
    - "{{ points_register.stdout_lines }}"
  when: (points_register.stdout | length > 0) and True
  tags:
    - mount_option_noexec_remote_filesystems
    - medium_severity
    - configure_strategy
    - low_complexity
    - medium_disruption
    - CCE-80436-9
    - NIST-800-53-AC-6
    - DISA-STIG-RHEL-07-021021

Rule   Mount Remote Filesystems with nosuid   [ref]

Add the nosuid option to the fourth column of /etc/fstab for the line which controls mounting of any NFS mounts.

Rationale:

NFS mounts should not present suid binaries to users. Only vendor-supplied suid executables should be installed to their default location on the local filesystem.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80240-5

References:  RHEL-07-021020, SV-86669r2_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, CCI-000366, 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

function include_mount_options_functions {
	:
}

# $1: type of filesystem
# $2: new mount point option
function ensure_mount_option_for_vfstype {
        local _vfstype="$1" _new_opt="$2" _vfstype_points=()
        _vfstype_points=($(grep -E "[[:space:]]$_vfstype[[:space:]]" /etc/fstab | awk '{print $2}'))

        for _vfstype_point in "${_vfstype_points[@]}"
        do
                ensure_mount_option_in_fstab "$_vfstype_point" "$_new_opt"
        done
}

# $1: mount point
# $2: new mount point option
function ensure_mount_option_in_fstab {
	local _mount_point="$1" _new_opt="$2" _mount_point_match_regexp="" _previous_mount_opts=""
	_mount_point_match_regexp="$(get_mount_point_regexp "$_mount_point")"

	if [ $(grep "$_mount_point_match_regexp" /etc/fstab | grep -c "$_new_opt" ) -eq 0 ]; then
		_previous_mount_opts=$(grep "$_mount_point_match_regexp" /etc/fstab | awk '{print $4}')
		sed -i "s|\(${_mount_point_match_regexp}.*${_previous_mount_opts}\)|\1,${_new_opt}|" /etc/fstab
	fi
}

# $1: mount point
function get_mount_point_regexp {
		printf "[[:space:]]%s[[:space:]]" "$1"
}

# $1: mount point
function assert_mount_point_in_fstab {
	local _mount_point_match_regexp
	_mount_point_match_regexp="$(get_mount_point_regexp "$1")"
	grep "$_mount_point_match_regexp" -q /etc/fstab \
		|| { echo "The mount point '$1' is not even in /etc/fstab, so we can't set up mount options" >&2; return 1; }
}

# $1: mount point
function remove_defaults_from_fstab_if_overriden {
	local _mount_point_match_regexp
	_mount_point_match_regexp="$(get_mount_point_regexp "$1")"
	if $(grep "$_mount_point_match_regexp" /etc/fstab | grep -q "defaults,")
	then
		sed -i "s|\(${_mount_point_match_regexp}.*\)defaults,|\1|" /etc/fstab
	fi
}

# $1: mount point
function ensure_partition_is_mounted {
	local _mount_point="$1"
	mkdir -p "$_mount_point" || return 1
	if mountpoint -q "$_mount_point"; then
		mount -o remount --target "$_mount_point"
	else
		mount --target "$_mount_point"
	fi
}

include_mount_options_functions

ensure_mount_option_for_vfstype "nfs[4]?" "nosuid"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Strategy:configure

- name: "Get nfs and nfs4 mount points, that don't have nosuid"
  shell: grep -E "[[:space:]]nfs[4]?[[:space:]]" /etc/fstab | grep -v "nosuid" | awk '{print $2}'
  register: points_register
  check_mode: no
  changed_when: False
  tags:
    - mount_option_nosuid_remote_filesystems
    - medium_severity
    - configure_strategy
    - low_complexity
    - medium_disruption
    - CCE-80240-5
    - NIST-800-53-AC-6
    - DISA-STIG-RHEL-07-021020
  

- name: "Add nosuid to mount points"
  shell: awk '$2=="{{ item }}"{$4=$4",nosuid"}1' /etc/fstab > fstab.tmp && mv fstab.tmp /etc/fstab
  with_items:
    - "{{ points_register.stdout_lines }}"
  when: (points_register.stdout | length > 0) and True
  tags:
    - mount_option_nosuid_remote_filesystems
    - medium_severity
    - configure_strategy
    - low_complexity
    - medium_disruption
    - CCE-80240-5
    - NIST-800-53-AC-6
    - DISA-STIG-RHEL-07-021020
Group   SSH Server   Group contains 1 group and 24 rules

[ref]   The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between two systems, as well as server authentication, through the use of public key cryptography. The implementation included with the system is called OpenSSH, and more detailed documentation is available from its website, http://www.openssh.org. Its server program is called sshd and provided by the RPM package openssh-server.

Group   Configure OpenSSH Server if Necessary   Group contains 20 rules

[ref]   If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file /etc/ssh/sshd_config. The following recommendations can be applied to this file. See the sshd_config(5) man page for more detailed information.

Rule   Disable SSH Support for User Known Hosts   [ref]

SSH can allow system users user host-based authentication to connect to systems if a cache of the remote systems public keys are available. This should be disabled.

To ensure this behavior is disabled, add or correct the following line in /etc/ssh/sshd_config:

IgnoreUserKnownHosts yes

Rationale:

Configuring this setting for the SSH daemon provides additional assurance that remove login via SSH will require a password, even in the event of misconfiguration elsewhere.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80372-6

References:  RHEL-07-040380, SV-86873r3_rule, 11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, AC-17(b), CM-6(a), PR.IP-1, FIA_AFL.1, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^IgnoreUserKnownHosts' 'yes' 'CCE-80372-6' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Disable SSH Support for User Known Hosts"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^IgnoreUserKnownHosts
    line: IgnoreUserKnownHosts yes
    insertbefore: ^Match
    firstmatch: yes 
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_disable_user_known_hosts
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80372-6
    - NIST-800-53-AC-17(b)
    - NIST-800-53-CM-6(a)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040380
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable SSH Access via Empty Passwords   [ref]

To explicitly disallow SSH login from accounts with empty passwords, add or correct the following line in /etc/ssh/sshd_config:

PermitEmptyPasswords no

Any accounts with empty passwords should be disabled immediately, and PAM configuration should prevent users from being able to assign themselves empty passwords.

Rationale:

Configuring this setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27471-2

References:  RHEL-07-010300, SV-86563r3_rule, 5.2.9, 11, 12, 13, 14, 15, 16, 18, 3, 5, 9, 5.5.6, APO01.06, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.03, DSS06.06, 3.1.1, 3.1.5, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 5.2, SR 7.6, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.2, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-3, AC-6, AC-17(b), CM-6(b), PR.AC-4, PR.AC-6, PR.DS-5, PR.IP-1, PR.PT-3, FIA_AFL.1, SRG-OS-000480-GPOS-00229, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^PermitEmptyPasswords' 'no' 'CCE-27471-2' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable SSH Access via Empty Passwords
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^PermitEmptyPasswords
    line: PermitEmptyPasswords no
    validate: /usr/sbin/sshd -t -f %s
  tags:
    - sshd_disable_empty_passwords
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27471-2
    - NIST-800-53-AC-3
    - NIST-800-53-AC-6
    - NIST-800-53-AC-17(b)
    - NIST-800-53-CM-6(b)
    - NIST-800-171-3.1.1
    - NIST-800-171-3.1.5
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-010300
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Set SSH Client Alive Max Count   [ref]

To ensure the SSH idle timeout occurs precisely when the ClientAliveInterval is set, edit /etc/ssh/sshd_config as follows:

ClientAliveCountMax 0

Rationale:

This ensures a user login will be terminated as soon as the ClientAliveInterval is reached.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27082-7

References:  RHEL-07-040340, SV-86865r4_rule, 5.2.12, 1, 12, 13, 14, 15, 16, 18, 3, 5, 7, 8, 5.5.6, APO13.01, BAI03.01, BAI03.02, BAI03.03, DSS01.03, DSS03.05, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10, 3.1.11, CCI-001133, CCI-002361, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 6.2, A.12.4.1, A.12.4.3, A.14.1.1, A.14.2.1, A.14.2.5, A.18.1.4, A.6.1.2, A.6.1.5, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5, AC-2(5), SA-8, AC-12, AC-17(b), DE.CM-1, DE.CM-3, PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.IP-2, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109A, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)


var_sshd_set_keepalive="0"
# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^ClientAliveCountMax' "$var_sshd_set_keepalive" 'CCE-27082-7' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: XCCDF Value var_sshd_set_keepalive # promote to variable
  set_fact:
    var_sshd_set_keepalive: !!str 0
  tags:
    - always

- name: Set SSH Client Alive Count
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^ClientAliveCountMax
    line: 'ClientAliveCountMax {{ var_sshd_set_keepalive }}'
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_set_keepalive
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27082-7
    - NIST-800-53-AC-2(5)
    - NIST-800-53-SA-8
    - NIST-800-53-AC-12
    - NIST-800-53-AC-17(b)
    - NIST-800-171-3.1.11
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-040340
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Set SSH Idle Timeout Interval   [ref]

SSH allows administrators to set an idle timeout interval. After this interval has passed, the idle user will be automatically logged out.

To set an idle timeout interval, edit the following line in /etc/ssh/sshd_config as follows:

ClientAliveInterval 600
The timeout interval is given in seconds. To have a timeout of 15 minutes, set interval to 900.

If a shorter timeout has already been set for the login shell, that value will preempt any SSH setting made here. Keep in mind that some processes may stop SSH from correctly detecting that the user is idle.

Rationale:

Terminating an idle ssh session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been let unattended.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27433-2

References:  RHEL-07-040320, SV-86861r4_rule, 5.2.12, 1, 12, 13, 14, 15, 16, 18, 3, 5, 7, 8, 5.5.6, APO13.01, BAI03.01, BAI03.02, BAI03.03, DSS01.03, DSS03.05, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10, 3.1.11, CCI-001133, CCI-002361, 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 6.2, A.12.4.1, A.12.4.3, A.14.1.1, A.14.2.1, A.14.2.5, A.18.1.4, A.6.1.2, A.6.1.5, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5, AC-2(5), SA-8(i), AC-12, AC-17(b), DE.CM-1, DE.CM-3, PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.IP-2, Req-8.1.8, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)


sshd_idle_timeout_value="600"
# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^ClientAliveInterval' $sshd_idle_timeout_value 'CCE-27433-2' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: XCCDF Value sshd_idle_timeout_value # promote to variable
  set_fact:
    sshd_idle_timeout_value: !!str 600
  tags:
    - always

- name: Set SSH Idle Timeout Interval
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^ClientAliveInterval
    line: "ClientAliveInterval {{ sshd_idle_timeout_value }}"
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_set_idle_timeout
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27433-2
    - NIST-800-53-AC-2(5)
    - NIST-800-53-SA-8(i)
    - NIST-800-53-AC-12
    - NIST-800-53-AC-17(b)
    - NIST-800-171-3.1.11
    - PCI-DSS-Req-8.1.8
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-040320
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Enable SSH Warning Banner   [ref]

To enable the warning banner and ensure it is consistent across the system, add or correct the following line in /etc/ssh/sshd_config:

Banner /etc/issue
Another section contains information on how to create an appropriate system-wide warning banner.

Rationale:

The warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious should ensure usage of a banner that does not provide easy attribution.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27314-4

References:  RHEL-07-040170, SV-86849r4_rule, 5.2.16, 1, 12, 15, 16, 5.5.6, DSS05.04, DSS05.10, DSS06.10, 3.1.9, CCI-000048, CCI-000050, CCI-001384, CCI-001385, CCI-001386, CCI-001387, CCI-001388, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-8(a), AC-8(b), AC-8(c)(1), AC-8(c)(2), AC-8(c)(3), AC-17(b), PR.AC-7, FMT_MOF_EXT.1, SRG-OS-000023-GPOS-00006, SRG-OS-000024-GPOS-00007, SRG-OS-000228-GPOS-00088, SRG-OS-000023-VMM-000060

Remediation Shell script:   (show)


grep -q ^Banner /etc/ssh/sshd_config && \
  sed -i "s/Banner.*/Banner \/etc\/issue/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
    echo "Banner /etc/issue" >> /etc/ssh/sshd_config
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Enable SSH Warning Banner
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^Banner
    line: Banner /etc/issue
    validate: /usr/sbin/sshd -t -f %s
  tags:
    - sshd_enable_warning_banner
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27314-4
    - NIST-800-53-AC-8(a)
    - NIST-800-53-AC-8(b)
    - NIST-800-53-AC-8(c)(1)
    - NIST-800-53-AC-8(c)(2)
    - NIST-800-53-AC-8(c)(3)
    - NIST-800-53-AC-17(b)
    - NIST-800-171-3.1.9
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-040170
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Use Only FIPS 140-2 Validated MACs   [ref]

Limit the MACs to those hash algorithms which are FIPS-approved. The following line in /etc/ssh/sshd_config demonstrates use of FIPS-approved MACs:

MACs hmac-sha2-512,hmac-sha2-256,hmac-sha1
The man page sshd_config(5) contains a list of supported MACs.

Only the following message authentication codes are FIPS 140-2 certified on Red Hat Enterprise Linux 7:
- hmac-sha1
- hmac-sha2-256
- hmac-sha2-512
- hmac-sha1-etm@openssh.com
- hmac-sha2-256-etm@openssh.com
- hmac-sha2-512-etm@openssh.com

Any combination of the above MACs will pass this check. Official FIPS 140-2 paperwork for Red Hat Enterprise Linux 7 can be found at http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp2630.pdf

Rationale:

DoD Information Systems are required to use FIPS-approved cryptographic hash functions. The only SSHv2 hash algorithms meeting this requirement is SHA2.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27455-5

References:  RHEL-07-040400, SV-86877r3_rule, 5.2.12, 1, 12, 13, 15, 16, 5, 8, APO01.06, APO13.01, DSS01.04, DSS05.02, DSS05.03, DSS05.04, DSS05.07, DSS06.02, DSS06.03, 3.1.13, 3.13.11, 3.13.8, CCI-001453, 164.308(b)(1), 164.308(b)(2), 164.312(e)(1), 164.312(e)(2)(i), 164.312(e)(2)(ii), 164.314(b)(2)(i), 4.3.3.5.1, 4.3.3.6.6, SR 1.1, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.6, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.11.2.6, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.6.2.1, A.6.2.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5, AC-17(b), AC-17(2), IA-7, SC-13, PR.AC-1, PR.AC-3, PR.DS-5, PR.PT-4, SRG-OS-000250-GPOS-00093, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)


sshd_approved_macs="hmac-sha2-512,hmac-sha2-256,hmac-sha1,hmac-sha1-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com"
# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^MACs' "$sshd_approved_macs" 'CCE-27455-5' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: XCCDF Value sshd_approved_macs # promote to variable
  set_fact:
    sshd_approved_macs: !!str hmac-sha2-512,hmac-sha2-256,hmac-sha1,hmac-sha1-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com
  tags:
    - always

- name: "Use Only Approved MACs"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^MACs
    line: "MACs {{ sshd_approved_macs }}"
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_use_approved_macs
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27455-5
    - NIST-800-53-AC-17(b)
    - NIST-800-53-AC-17(2)
    - NIST-800-53-IA-7
    - NIST-800-53-SC-13
    - NIST-800-171-3.1.13
    - NIST-800-171-3.13.11
    - NIST-800-171-3.13.8
    - DISA-STIG-RHEL-07-040400
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Do Not Allow SSH Environment Options   [ref]

To ensure users are not able to override environment options to the SSH daemon, add or correct the following line in /etc/ssh/sshd_config:

PermitUserEnvironment no

Rationale:

SSH environment options potentially allow users to bypass access restriction in some configurations.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27363-1

References:  RHEL-07-010460, SV-86581r3_rule, 5.2.10, 11, 3, 9, 5.5.6, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, AC-17(b), CM-6(b), PR.IP-1, SRG-OS-000480-GPOS-00229, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^PermitUserEnvironment' 'no' 'CCE-27363-1' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Do Not Allow SSH Environment Options
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^PermitUserEnvironment
    line: PermitUserEnvironment no
    validate: /usr/sbin/sshd -t -f %s
  tags:
    - sshd_do_not_permit_user_env
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27363-1
    - NIST-800-53-AC-17(b)
    - NIST-800-53-CM-6(b)
    - NIST-800-171-3.1.12
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-010460
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable Kerberos Authentication   [ref]

Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like Kerberos. To disable Kerberos authentication, add or correct the following line in the /etc/ssh/sshd_config file:

KerberosAuthentication no

Rationale:

Kerberos authentication for SSH is often implemented using GSSAPI. If Kerberos is enabled through SSH, the SSH daemon provides a means of access to the system's Kerberos implementation. Vulnerabilities in the system's Kerberos implementations may be subject to exploitation.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80221-5

References:  RHEL-07-040440, SV-86885r3_rule, 11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000368, CCI-000318, CCI-001812, CCI-001813, CCI-001814, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, CM-6(c), PR.IP-1, FIA_AFL.1, SRG-OS-000364-GPOS-00151, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^KerberosAuthentication' 'no' 'CCE-80221-5' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Disable Kerberos Authentication"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: (?i)^#?kerberosauthentication
    line: KerberosAuthentication no
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_disable_kerb_auth
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80221-5
    - NIST-800-53-CM-6(c)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040440
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Allow Only SSH Protocol 2   [ref]

Only SSH protocol version 2 connections should be permitted. The default setting in /etc/ssh/sshd_config is correct, and can be verified by ensuring that the following line appears:

Protocol 2

Warning:  As of openssh-server version 7.4 and above, the only protocol supported is version 2, and line
Protocol 2
in /etc/ssh/sshd_config is not necessary.
Rationale:

SSH protocol version 1 is an insecure implementation of the SSH protocol and has many well-known vulnerability exploits. Exploits of the SSH daemon could provide immediate root access to the system.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27320-1

References:  RHEL-07-040390, SV-86875r4_rule, 5.2.2, 1, 12, 15, 16, 5, 8, 5.5.6, APO13.01, DSS01.04, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.10, 3.1.13, 3.5.4, CCI-000197, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.4, SR 1.1, SR 1.10, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.6, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.13.1.1, A.13.2.1, A.14.1.3, A.18.1.4, A.6.2.1, A.6.2.2, A.7.1.1, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3, AC-17(b), AC-17(8).1(ii), IA-5(1)(c), PR.AC-1, PR.AC-3, PR.AC-6, PR.AC-7, PR.PT-4, SRG-OS-000074-GPOS-00042, SRG-OS-000480-GPOS-00227, SRG-OS-000033-VMM-000140

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^Protocol' '2' 'CCE-27320-1' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict

- name: "Allow Only SSH Protocol 2"
  lineinfile:
    dest: /etc/ssh/sshd_config
    regexp: "^Protocol [0-9]"
    line: "Protocol 2"
    validate: /usr/sbin/sshd -t -f %s
  #notify: :reload ssh
  tags:
    - sshd_allow_only_protocol2
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27320-1
    - NIST-800-53-AC-17(b)
    - NIST-800-53-AC-17(8).1(ii)
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.5.4
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-040390
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable SSH Support for .rhosts Files   [ref]

SSH can emulate the behavior of the obsolete rsh command in allowing users to enable insecure access to their accounts via .rhosts files.

To ensure this behavior is disabled, add or correct the following line in /etc/ssh/sshd_config:

IgnoreRhosts yes

Rationale:

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27377-1

References:  RHEL-07-040350, SV-86867r3_rule, 5.2.6, 11, 12, 14, 15, 16, 18, 3, 5, 9, 5.5.6, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.03, DSS06.06, 3.1.12, CCI-000366, 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.6.1.2, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-3, AC-17(b), CM-6(a), PR.AC-4, PR.AC-6, PR.IP-1, PR.PT-3, FIA_AFL.1, SRG-OS-000480-GPOS-00227, SRG-OS-000107-VMM-000530

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^IgnoreRhosts' 'yes' 'CCE-27377-1' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable SSH Support for .rhosts Files
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^IgnoreRhosts
    line: IgnoreRhosts yes
    validate: /usr/sbin/sshd -t -f %s
  tags:
    - sshd_disable_rhosts
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27377-1
    - NIST-800-53-AC-3
    - NIST-800-53-AC-17(b)
    - NIST-800-53-CM-6(a)
    - NIST-800-171-3.1.12
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-040350
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable SSH Support for Rhosts RSA Authentication   [ref]

SSH can allow authentication through the obsolete rsh command through the use of the authenticating user's SSH keys. This should be disabled.

To ensure this behavior is disabled, add or correct the following line in /etc/ssh/sshd_config:

RhostsRSAAuthentication no

Warning:  As of openssh-server version 7.4 and above, the RhostsRSAAuthentication option has been deprecated, and the line
RhostsRSAAuthentication no
in /etc/ssh/sshd_config is not necessary.
Rationale:

Configuring this setting for the SSH daemon provides additional assurance that remove login via SSH will require a password, even in the event of misconfiguration elsewhere.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80373-4

References:  RHEL-07-040330, SV-86863r4_rule, 11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, CM-6(a), AC-17(b), PR.IP-1, FIA_AFL.1, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^RhostsRSAAuthentication' 'no' 'CCE-80373-4' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable SSH Support for Rhosts RSA Authentication
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^RhostsRSAAuthentication
    line: RhostsRSAAuthentication no
    validate: /usr/sbin/sshd -t -f %s
  tags:
    - sshd_disable_rhosts_rsa
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80373-4
    - NIST-800-53-CM-6(a)
    - NIST-800-53-AC-17(b)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040330
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Enable Encrypted X11 Forwarding   [ref]

By default, remote X11 connections are not encrypted when initiated by users. SSH has the capability to encrypt remote X11 connections when SSH's X11Forwarding option is enabled.

To enable X11 Forwarding, add or correct the following line in /etc/ssh/sshd_config:

X11Forwarding yes

Rationale:

Open X displays allow an attacker to capture keystrokes and to execute commands remotely.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80226-4

References:  RHEL-07-040710, SV-86927r4_rule, 5.2.4, 1, 11, 12, 13, 15, 16, 18, 20, 3, 4, 6, 9, BAI03.08, BAI07.04, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS03.01, 3.1.13, CCI-000366, 4.3.4.3.2, 4.3.4.3.3, 4.4.3.3, SR 7.6, A.12.1.1, A.12.1.2, A.12.1.4, A.12.5.1, A.12.6.2, A.13.1.1, A.13.1.2, A.14.2.2, A.14.2.3, A.14.2.4, CM-2(1)(b), DE.AE-1, PR.DS-7, PR.IP-1, SRG-OS-000480-GPOS-00227

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Enable Encrypted X11 Forwarding
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^X11Forwarding
    line: X11Forwarding yes
    validate: /usr/sbin/sshd -t -f %s
  tags:
    - sshd_enable_x11_forwarding
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80226-4
    - NIST-800-53-CM-2(1)(b)
    - NIST-800-171-3.1.13
    - DISA-STIG-RHEL-07-040710
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Use Only FIPS 140-2 Validated Ciphers   [ref]

Limit the ciphers to those algorithms which are FIPS-approved. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. The following line in /etc/ssh/sshd_config demonstrates use of FIPS-approved ciphers:

Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc
The man page sshd_config(5) contains a list of supported ciphers.

The following ciphers are FIPS 140-2 certified on Red Hat Enterprise Linux 7:
- aes128-ctr
- aes192-ctr
- aes256-ctr
- aes128-cbc
- aes192-cbc
- aes256-cbc
- 3des-cbc
- rijndael-cbc@lysator.liu.se

Any combination of the above ciphers will pass this check. Official FIPS 140-2 paperwork for Red Hat Enterprise Linux 7 can be found at http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp2630.pdf

Rationale:

Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore cannot be relied upon to provide confidentiality or integrity, and system data may be compromised.
Operating systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules.
FIPS 140-2 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets industry and government requirements. For government systems, this allows Security Levels 1, 2, 3, or 4 for use on Red Hat Enterprise Linux 7.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27295-5

References:  RHEL-07-040110, SV-86845r3_rule, 5.2.10, 1, 11, 12, 14, 15, 16, 18, 3, 5, 6, 8, 9, 5.5.6, APO11.04, APO13.01, BAI03.05, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.04, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.06, DSS06.10, MEA02.01, 3.1.13, 3.13.11, 3.13.8, CCI-000068, CCI-000366, CCI-000803, 164.308(b)(1), 164.308(b)(2), 164.312(e)(1), 164.312(e)(2)(i), 164.312(e)(2)(ii), 164.314(b)(2)(i), 4.3.3.2.2, 4.3.3.3.9, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.10, SR 2.11, SR 2.12, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 2.8, SR 2.9, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.12.1.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.5.1, A.12.6.2, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.18.1.4, A.6.1.2, A.6.2.1, A.6.2.2, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.1, A.9.4.2, A.9.4.3, A.9.4.4, A.9.4.5, AC-3, AC-17(b), AC-17(2), AU-10(5), CM-6(b), IA-5(1)(c), IA-7, SI-7, PR.AC-1, PR.AC-3, PR.AC-4, PR.AC-6, PR.AC-7, PR.IP-1, PR.PT-1, PR.PT-3, PR.PT-4, SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061, SRG-OS-000125-GPOS-00065, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173, SRG-OS-000033-VMM-000140, SRG-OS-000478-VMM-001980

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^Ciphers' 'aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc' 'CCE-27295-5' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Use Only Approved Ciphers
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^Ciphers
    line: Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_use_approved_ciphers
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27295-5
    - NIST-800-53-AC-3
    - NIST-800-53-AC-17(b)
    - NIST-800-53-AC-17(2)
    - NIST-800-53-AU-10(5)
    - NIST-800-53-CM-6(b)
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-53-IA-7
    - NIST-800-53-SI-7
    - NIST-800-171-3.1.13
    - NIST-800-171-3.13.11
    - NIST-800-171-3.13.8
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-040110
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable Host-Based Authentication   [ref]

SSH's cryptographic host-based authentication is more secure than .rhosts authentication. However, it is not recommended that hosts unilaterally trust one another, even within an organization.

To disable host-based authentication, add or correct the following line in /etc/ssh/sshd_config:

HostbasedAuthentication no

Rationale:

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27413-4

References:  RHEL-07-010470, SV-86583r3_rule, 5.2.7, 11, 12, 14, 15, 16, 18, 3, 5, 9, 5.5.6, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.03, DSS06.06, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.3, 4.3.3.5.4, 4.3.3.5.5, 4.3.3.5.6, 4.3.3.5.7, 4.3.3.5.8, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.1, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.3.2, 4.3.4.3.3, SR 1.1, SR 1.10, SR 1.11, SR 1.12, SR 1.13, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.6, SR 1.7, SR 1.8, SR 1.9, SR 2.1, SR 2.2, SR 2.3, SR 2.4, SR 2.5, SR 2.6, SR 2.7, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.6.1.2, A.7.1.1, A.9.1.2, A.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-3, AC-17, CM-6(b), PR.AC-4, PR.AC-6, PR.IP-1, PR.PT-3, FIA_AFL.1, SRG-OS-000480-GPOS-00229, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

grep -q ^HostbasedAuthentication /etc/ssh/sshd_config && \
  sed -i "s/HostbasedAuthentication.*/HostbasedAuthentication no/g" /etc/ssh/sshd_config
if ! [ $? -eq 0 ]; then
    echo "HostbasedAuthentication no" >> /etc/ssh/sshd_config
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable Host-Based Authentication
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^HostbasedAuthentication
    line: HostbasedAuthentication no
  tags:
    - disable_host_auth
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27413-4
    - NIST-800-53-AC-3
    - NIST-800-53-AC-17
    - NIST-800-53-CM-6(b)
    - NIST-800-171-3.1.12
    - CJIS-5.5.6
    - DISA-STIG-RHEL-07-010470
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Enable Use of Strict Mode Checking   [ref]

SSHs StrictModes option checks file and ownership permissions in the user's home directory .ssh folder before accepting login. If world- writable permissions are found, logon is rejected. To enable StrictModes in SSH, add or correct the following line in the /etc/ssh/sshd_config file:

StrictModes yes

Rationale:

If other users have access to modify user-specific SSH configuration files, they may be able to log into the system as another user.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80222-3

References:  RHEL-07-040450, SV-86887r3_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, AC-17(b), PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^StrictModes' 'yes' 'CCE-80222-3' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Enable Use of Strict Mode Checking"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: (?i)^#?strictmodes
    line: StrictModes yes
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_enable_strictmodes
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80222-3
    - NIST-800-53-AC-6
    - NIST-800-53-AC-17(b)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040450
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Enable Use of Privilege Separation   [ref]

When enabled, SSH will create an unprivileged child process that has the privilege of the authenticated user. To enable privilege separation in SSH, add or correct the following line in the /etc/ssh/sshd_config file:

UsePrivilegeSeparation sandbox

Rationale:

SSH daemon privilege separation causes the SSH process to drop root privileges when not needed which would decrease the impact of software vulnerabilities in the unprivileged section.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80223-1

References:  RHEL-07-040460, SV-86889r3_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, AC-17(b), PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^UsePrivilegeSeparation' 'sandbox' 'CCE-80223-1' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Enable use of Privilege Separation"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: (?i)^#?useprivilegeseparation
    line: UsePrivilegeSeparation sandbox
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_use_priv_separation
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80223-1
    - NIST-800-53-AC-6
    - NIST-800-53-AC-17(b)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040460
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Enable SSH Print Last Log   [ref]

When enabled, SSH will display the date and time of the last successful account logon. To enable LastLog in SSH, add or correct the following line in the /etc/ssh/sshd_config file:

PrintLastLog yes

Rationale:

Providing users feedback on when account accesses last occurred facilitates user recognition and reporting of unauthorized account use.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80225-6

References:  RHEL-07-040360, SV-86869r3_rule, 1, 12, 15, 16, DSS05.04, DSS05.10, DSS06.10, CCI-000366, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-9, AC-17(b), PR.AC-7, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^PrintLastLog' 'yes' 'CCE-80225-6' '%s %s'
Remediation Ansible snippet:   (show)

- name: Print last log
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: ^PrintLastLog
    line: PrintLastLog yes
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_print_last_log
    - medium_severity
    - CCE-80225-6
    - NIST-800-53-AC-9
    - NIST-800-53-AC-17(b)
    - DISA-STIG-RHEL-07-040360
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable GSSAPI Authentication   [ref]

Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. To disable GSSAPI authentication, add or correct the following line in the /etc/ssh/sshd_config file:

GSSAPIAuthentication no

Rationale:

GSSAPI authentication is used to provide additional authentication mechanisms to applications. Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote hosts, increasing the attack surface of the system.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80220-7

References:  RHEL-07-040430, SV-86883r3_rule, 11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000368, CCI-000318, CCI-001812, CCI-001813, CCI-001814, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, AC-17(b), CM-6(c), PR.IP-1, FIA_AFL.1, SRG-OS-000364-GPOS-00151, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^GSSAPIAuthentication' 'no' 'CCE-80220-7' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Disable GSSAPI Authentication"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: (?i)^#?gssapiauthentication
    line: GSSAPIAuthentication no
    validate: /usr/sbin/sshd -t -f %s
  #notify: sshd -t -f %s
  tags:
    - sshd_disable_gssapi_auth
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80220-7
    - NIST-800-53-AC-17(b)
    - NIST-800-53-CM-6(c)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040430
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Disable Compression Or Set Compression to delayed   [ref]

Compression is useful for slow network connections over long distances but can cause performance issues on local LANs. If use of compression is required, it should be enabled only after a user has authenticated; otherwise , it should be disabled. To disable compression or delay compression until after a user has successfully authenticated, add or correct the following line in the /etc/ssh/sshd_config file:

Compression no
or
Compression delayed

Rationale:

If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially wih root privileges.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80224-9

References:  RHEL-07-040470, SV-86891r3_rule, 11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000366, 164.308(a)(4)(i), 164.308(b)(1), 164.308(b)(3), 164.310(b), 164.312(e)(1), 164.312(e)(2)(ii), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, CM-6(b), PR.IP-1, SRG-OS-000480-GPOS-00227, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/ssh/sshd_config' '^Compression' 'no' 'CCE-80224-9' '%s %s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Disable Compression or Set Compression to delayed"
  lineinfile:
    create: yes
    dest: /etc/ssh/sshd_config
    regexp: (?i)^#?compression
    line: Compression delayed
    validate: /usr/sbin/sshd -t -f %s
  #notify: restart sshd
  tags:
    - sshd_disable_compression
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80224-9
    - NIST-800-53-CM-6(b)
    - NIST-800-171-3.1.12
    - DISA-STIG-RHEL-07-040470
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Install the OpenSSH Server Package   [ref]

The openssh-server package should be installed. The openssh-server package can be installed with the following command:

$ sudo yum install openssh-server

Rationale:

Without protection of the transmitted information, confidentiality, and integrity may be compromised because unprotected communications can be intercepted and either read or altered.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80215-7

References:  RHEL-07-040300, SV-86857r3_rule, 13, 14, APO01.06, DSS05.02, DSS05.04, DSS05.07, DSS06.02, DSS06.06, CCI-002418, CCI-002420, CCI-002421, CCI-002422, SR 3.1, SR 3.8, SR 4.1, SR 4.2, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, SC-8, PR.DS-2, PR.DS-5, SRG-OS-000423-GPOS-00187, SRG-OS-000423-GPOS-00188, SRG-OS-000423-GPOS-00189, SRG-OS000423-GPOS-00190

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable
# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install openssh-server
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: Ensure openssh-server is installed
  package:
    name: openssh-server
    state: present
  tags:
    - package_openssh-server_installed
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
    - CCE-80215-7
    - NIST-800-53-SC-8
    - DISA-STIG-RHEL-07-040300
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
include install_openssh-server

class install_openssh-server {
  package { 'openssh-server':
    ensure => 'installed',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable

package --add=openssh-server

Rule   Enable the OpenSSH Service   [ref]

The SSH server service, sshd, is commonly needed. The sshd service can be enabled with the following command:

$ sudo systemctl enable sshd.service

Rationale:

Without protection of the transmitted information, confidentiality, and integrity may be compromised because unprotected communications can be intercepted and either read or altered.

This checklist item applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, etc). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80216-5

References:  RHEL-07-040310, SV-86859r3_rule, 13, 14, APO01.06, DSS05.02, DSS05.04, DSS05.07, DSS06.02, DSS06.06, 3.1.13, 3.5.4, 3.13.8, CCI-002418, CCI-002420, CCI-002421, CCI-002422, SR 3.1, SR 3.8, SR 4.1, SR 4.2, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, SC-8, PR.DS-2, PR.DS-5, SRG-OS-000423-GPOS-00187, SRG-OS-000423-GPOS-00188, SRG-OS-000423-GPOS-00189, SRG-OS000423-GPOS-00190

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" start 'sshd.service'
"$SYSTEMCTL_EXEC" enable 'sshd.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: Enable service sshd
  service:
    name: sshd
    enabled: "yes"
    state: "started"
  tags:
    - service_sshd_enabled
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
    - CCE-80216-5
    - NIST-800-53-SC-8
    - NIST-800-171-3.1.13
    - NIST-800-171-3.5.4
    - NIST-800-171-3.13.8
    - DISA-STIG-RHEL-07-040310
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Verify Permissions on SSH Server Public *.pub Key Files   [ref]

To properly set the permissions of /etc/ssh/*.pub, run the command:

$ sudo chmod 0644 /etc/ssh/*.pub

Rationale:

If a public host key file is modified by an unauthorized user, the SSH service may be compromised.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27311-0

References:  RHEL-07-040410, SV-86879r2_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.1.13, 3.13.10, CCI-000366, 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure
find /etc/ssh -regex '^/etc/ssh/.*.pub$' -exec chmod 0644 {} \;
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Find /etc/ssh file(s)
  find:
    paths: "/etc/ssh"
    patterns: "^.*.pub$"
  register: files_found
  tags:
    - file_permissions_sshd_pub_key
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-27311-0
    - NIST-800-53-AC-6
    - NIST-800-171-3.1.13
    - NIST-800-171-3.13.10
    - DISA-STIG-RHEL-07-040410

- name: Set permissions for /etc/ssh file(s)
  file:
    path: "{{ item.path }}"
    mode: 0644
  with_items:
    - "{{ files_found.files }}"
  tags:
    - file_permissions_sshd_pub_key
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-27311-0
    - NIST-800-53-AC-6
    - NIST-800-171-3.1.13
    - NIST-800-171-3.13.10
    - DISA-STIG-RHEL-07-040410
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Remediation Puppet snippet:   (show)

include ssh_public_key_perms

class ssh_public_key_perms {
  exec { 'sshd_pub_key':
    command => "chmod 0644 /etc/ssh/*.pub",
    path    => '/bin:/usr/bin'
  }
}

Rule   Verify Permissions on SSH Server Private *_key Key Files   [ref]

To properly set the permissions of /etc/ssh/*_key, run the command:

$ sudo chmod 0640 /etc/ssh/*_key

Rationale:

If an unauthorized user obtains the private SSH host key file, the host could be impersonated.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27485-2

References:  RHEL-07-040420, SV-86881r3_rule, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.1.13, 3.13.10, CCI-000366, 4.3.3.7.3, SR 2.1, SR 5.2, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, AC-17, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure
find /etc/ssh -regex '^/etc/ssh/.*_key$' -exec chmod 0640 {} \;
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Find /etc/ssh file(s)
  find:
    paths: "/etc/ssh"
    patterns: "^.*_key$"
  register: files_found
  tags:
    - file_permissions_sshd_private_key
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-27485-2
    - NIST-800-53-AC-6
    - NIST-800-53-AC-17
    - NIST-800-171-3.1.13
    - NIST-800-171-3.13.10
    - DISA-STIG-RHEL-07-040420

- name: Set permissions for /etc/ssh file(s)
  file:
    path: "{{ item.path }}"
    mode: 0640
  with_items:
    - "{{ files_found.files }}"
  tags:
    - file_permissions_sshd_private_key
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-27485-2
    - NIST-800-53-AC-6
    - NIST-800-53-AC-17
    - NIST-800-171-3.1.13
    - NIST-800-171-3.13.10
    - DISA-STIG-RHEL-07-040420
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Remediation Puppet snippet:   (show)

include ssh_private_key_perms

class ssh_private_key_perms {
  exec { 'sshd_priv_key':
    command => "chmod 0640 /etc/ssh/*_key",
    path    => '/bin:/usr/bin'
  }
}
Group   System Settings   Group contains 70 groups and 196 rules

[ref]   Contains rules that check correct system settings.

Group   Installing and Maintaining Software   Group contains 14 groups and 34 rules

[ref]   The following sections contain information on security-relevant choices during the initial operating system installation process and the setup of software updates.

Group   Disk Partitioning   Group contains 4 rules

[ref]   To ensure separation and protection of data, there are top-level system directories which should be placed on their own physical partition or logical volume. The installer's default partitioning scheme creates separate logical volumes for /, /boot, and swap.

  • If starting with any of the default layouts, check the box to \"Review and modify partitioning.\" This allows for the easy creation of additional logical volumes inside the volume group already created, though it may require making /'s logical volume smaller to create space. In general, using logical volumes is preferable to using partitions because they can be more easily adjusted later.
  • If creating a custom layout, create the partitions mentioned in the previous paragraph (which the installer will require anyway), as well as separate ones described in the following sections.
If a system has already been installed, and the default partitioning scheme was used, it is possible but nontrivial to modify it to create separate logical volumes for the directories listed above. The Logical Volume Manager (LVM) makes this possible. See the LVM HOWTO at http://tldp.org/HOWTO/LVM-HOWTO/ for more detailed information on LVM.

Rule   Ensure /home Located On Separate Partition   [ref]

If user home directories will be stored locally, create a separate partition for /home at installation time (or migrate it later using LVM). If /home will be mounted from another system such as an NFS server, then creating a separate partition is not necessary at installation time, and the mountpoint can instead be configured later.

Rationale:

Ensuring that /home is mounted on its own partition enables the setting of more restrictive mount options, and also helps ensure that users cannot trivially fill partitions used for log or audit data storage.

Severity: 
low
Identifiers and References

Identifiers:  CCE-80144-9

References:  RHEL-07-021310, SV-86683r2_rule, 1.1.13, 12, 15, 8, APO13.01, DSS05.02, CCI-000366, CCI-001208, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.13.1.1, A.13.2.1, A.14.1.3, SC-32(1), PR.PT-4, SRG-OS-000480-GPOS-00227

Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:high
Strategy:enable

part /home

Rule   Ensure /var Located On Separate Partition   [ref]

The /var directory is used by daemons and other system services to store frequently-changing data. Ensure that /var has its own partition or logical volume at installation time, or migrate it using LVM.

Rationale:

Ensuring that /var is mounted on its own partition enables the setting of more restrictive mount options. This helps protect system services such as daemons or other programs which use it. It is not uncommon for the /var directory to contain world-writable directories installed by other software packages.

Severity: 
low
Identifiers and References

Identifiers:  CCE-26404-4

References:  RHEL-07-021320, SV-86685r2_rule, 1.1.6, 12, 15, 8, APO13.01, DSS05.02, CCI-000366, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.13.1.1, A.13.2.1, A.14.1.3, SC-32(1), PR.PT-4, SRG-OS-000480-GPOS-00227, SRG-OS-000341-VMM-001220

Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:high
Strategy:enable

part /var

Rule   Ensure /tmp Located On Separate Partition   [ref]

The /tmp directory is a world-writable directory used for temporary file storage. Ensure it has its own partition or logical volume at installation time, or migrate it using LVM.

Rationale:

The /tmp partition is used as temporary storage by many programs. Placing /tmp in its own partition enables the setting of more restrictive mount options, which can help protect programs which use it.

Severity: 
low
Identifiers and References

Identifiers:  CCE-27173-4

References:  RHEL-07-021340, SV-86689r2_rule, 1.1.2, 12, 15, 8, APO13.01, DSS05.02, CCI-000366, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.13.1.1, A.13.2.1, A.14.1.3, SC-32(1), PR.PT-4, SRG-OS-000480-GPOS-00227

Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:high
Strategy:enable

part /tmp

Rule   Ensure /var/log/audit Located On Separate Partition   [ref]

Audit logs are stored in the /var/log/audit directory. Ensure that it has its own partition or logical volume at installation time, or migrate it later using LVM. Make absolutely certain that it is large enough to store all audit logs that will be created by the auditing daemon.

Rationale:

Placing /var/log/audit in its own partition enables better separation between audit files and other files, and helps ensure that auditing cannot be halted due to the partition running out of space.

Severity: 
low
Identifiers and References

Identifiers:  CCE-26971-2

References:  RHEL-07-021330, SV-86687r6_rule, 1.1.12, 1, 12, 13, 14, 15, 16, 2, 3, 5, 6, 8, APO11.04, APO13.01, BAI03.05, BAI04.04, DSS05.02, DSS05.04, DSS05.07, MEA02.01, CCI-000366, 164.312(a)(2)(ii), 4.3.3.3.9, 4.3.3.5.8, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 2.10, SR 2.11, SR 2.12, SR 2.8, SR 2.9, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.2, SR 7.6, A.12.1.3, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.17.2.1, AU-4, AU-9, SC-32(1), PR.DS-4, PR.PT-1, PR.PT-4, SRG-OS-000480-GPOS-00227, SRG-OS-000341-VMM-001220

Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:high
Strategy:enable

part /var/log/audit
Group   Sudo   Group contains 2 rules

[ref]   Sudo, which stands for \"su 'do'\", provides the ability to delegate authority to certain users, groups of users, or system administrators. When configured for system users and/or groups, Sudo can allow a user or group to execute privileged commands that normally only root is allowed to execute.

For more information on Sudo and addition Sudo configuration options, see https://www.sudo.ws.

Rule   Ensure Users Re-Authenticate for Privilege Escalation - sudo !authenticate   [ref]

The sudo !authenticate option, when specified, allows a user to execute commands using sudo without having to authenticate. This should be disabled by making sure that the !authenticate option does not exist in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/.

Rationale:

Without re-authentication, users may access resources or perform tasks for which they do not have authorization.

When operating systems provide the capability to escalate a functional capability, it is critical that the user re-authenticate.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80350-2

References:  RHEL-07-010350, SV-86573r3_rule, NT28(R5), 1, 12, 15, 16, 5, DSS05.04, DSS05.10, DSS06.03, DSS06.10, CCI-002038, 4.3.3.5.1, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3, IA-11, PR.AC-1, PR.AC-7, SRG-OS-000373-GPOS-00156, SRG-OS-000373-GPOS-00157, SRG-OS-000373-GPOS-00158

Rule   Ensure Users Re-Authenticate for Privilege Escalation - sudo NOPASSWD   [ref]

The sudo NOPASSWD tag, when specified, allows a user to execute commands using sudo without having to authenticate. This should be disabled by making sure that the NOPASSWD tag does not exist in /etc/sudoers configuration file or any sudo configuration snippets in /etc/sudoers.d/.

Rationale:

Without re-authentication, users may access resources or perform tasks for which they do not have authorization.

When operating systems provide the capability to escalate a functional capability, it is critical that the user re-authenticate.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80351-0

References:  RHEL-07-010340, SV-86571r3_rule, NT28(R5), 1, 12, 15, 16, 5, DSS05.04, DSS05.10, DSS06.03, DSS06.10, CCI-002038, 4.3.3.5.1, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.2, A.9.2.3, A.9.2.4, A.9.2.6, A.9.3.1, A.9.4.2, A.9.4.3, IA-11, PR.AC-1, PR.AC-7, SRG-OS-000373-GPOS-00156, SRG-OS-000373-GPOS-00157, SRG-OS-000373-GPOS-00158

Group   System and Software Integrity   Group contains 7 groups and 12 rules

[ref]   System and software integrity can be gained by installing antivirus, increasing system encryption strength with FIPS, verifying installed software, enabling SELinux, installing an Intrusion Prevention System, etc. However, installing or enabling integrity checking tools cannot prevent intrusions, but they can detect that an intrusion may have occurred. Requirements for integrity checking may be highly dependent on the environment in which the system will be used. Snapshot-based approaches such as AIDE may induce considerable overhead in the presence of frequent software updates.

Group   Operating System Vendor Support and Certification   Group contains 1 rule

[ref]   The assurance of a vendor to provide operating system support and maintenance for their product is an important criterion to ensure product stability and security over the life of the product. A certified product that follows the necessary standards and government certification requirements guarantees that known software vulnerabilities will be remediated, and proper guidance for protecting and securing the operating system will be given.

Rule   The Installed Operating System Is Vendor Supported   [ref]

The installed operating system must be maintained by a vendor. Red Hat Enterprise Linux is supported by Red Hat, Inc. As the Red Hat Enterprise Linux vendor, Red Hat, Inc. is responsible for providing security patches.

Warning:  There is no remediation besides switching to a different operating system.
Rationale:

An operating system is considered "supported" if the vendor continues to provide security patches for the product. With an unsupported release, it will not be possible to resolve any security issue discovered in the system software.

Severity: 
high
Identifiers and References

References:  RHEL-07-020250, SV-86621r3_rule, 18, 20, 4, APO12.01, APO12.02, APO12.03, APO12.04, BAI03.10, DSS05.01, DSS05.02, CCI-000366, 4.2.3, 4.2.3.12, 4.2.3.7, 4.2.3.9, A.12.6.1, A.14.2.3, A.16.1.3, A.18.2.2, A.18.2.3, SI-2(c), ID.RA-1, PR.IP-12, SRG-OS-000480-GPOS-00227

Group   Federal Information Processing Standard (FIPS)   Group contains 1 rule

[ref]   The Federal Information Processing Standard (FIPS) is a computer security standard which is developed by the U.S. Government and industry working groups to validate the quality of cryptographic modules. The FIPS standard provides four security levels to ensure adequate coverage of different industries, implementation of cryptographic modules, and organizational sizes and requirements.

FIPS 140-2 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets industry and government requirements. For government systems, this allows Security Levels 1, 2, 3, or 4 for use on Red Hat Enterprise Linux 7.

See http://csrc.nist.gov/publications/PubsFIPS.html for more information.

Rule   Enable FIPS Mode in GRUB2   [ref]

To ensure FIPS mode is enabled, install package dracut-fips, and rebuild initramfs by running the following commands:

$ sudo yum install dracut-fips
dracut -f
After the dracut command has been run, add the argument fips=1 to the default GRUB 2 command line for the Linux operating system in /etc/default/grub, in the manner below:
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=VolGroup/LogVol06 rd.lvm.lv=VolGroup/lv_swap rhgb quiet rd.shell=0 fips=1"
Finally, rebuild the grub.cfg file by using the
grub2-mkconfig -o
command as follows:
  • On BIOS-based machines, issue the following command as root:
    ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
  • On UEFI-based machines, issue the following command as root:
    ~]# grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

Warning:  Running
dracut -f
will overwrite the existing initramfs file.
Warning:  The system needs to be rebooted for these changes to take effect.
Warning:  The ability to enable FIPS does not denote FIPS compliancy or certification. Red Hat, Inc. and Red Hat Enterprise Linux are respectively FIPS certified and compliant. Community projects such as CentOS, Scientific Linux, Fedora, etc. do not necessarily meet FIPS certification and compliancy. Therefore, non-certified vendors and/or projects do not meet this requirement even if technically feasible.

See http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/1401vend.htm for a list of FIPS certified vendors.
Rationale:

Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80359-3

References:  RHEL-07-021350, SV-86691r4_rule, 12, 15, 8, 5.10.1.2, APO13.01, DSS01.04, DSS05.02, DSS05.03, 3.13.8, 3.13.11, CCI-000068, CCI-002450, 4.3.3.6.6, SR 1.13, SR 2.6, SR 3.1, SR 3.5, SR 3.8, SR 4.1, SR 4.3, SR 5.1, SR 5.2, SR 5.3, SR 7.1, SR 7.6, A.11.2.6, A.13.1.1, A.13.2.1, A.14.1.3, A.6.2.1, A.6.2.2, IA-5, SC-13, AC-17(2), PR.AC-3, PR.PT-4, SRG-OS-000033-GPOS-00014, SRG-OS-000396-GPOS-00176, SRG-OS-000478-GPOS-00223

Remediation Shell script:   (show)

function disable_prelink {
	# Disable prelinking and don't even check
	# whether it is installed.
	if grep -q ^PRELINKING /etc/sysconfig/prelink
	then
		sed -i 's/^PRELINKING[:blank:]*=[:blank:]*[:alpha:]*/PRELINKING=no/' /etc/sysconfig/prelink
	else
		printf '\n' >> /etc/sysconfig/prelink
		printf '%s\n' '# Set PRELINKING=no per security requirements' 'PRELINKING=no' >> /etc/sysconfig/prelink
	fi

	# Undo previous prelink changes to binaries if prelink is available.
	if test -x /usr/sbin/prelink; then
		/usr/sbin/prelink -ua
	fi
}

disable_prelink
# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install dracut-fips

dracut -f

# Correct the form of default kernel command line in  grub
if grep -q '^GRUB_CMDLINE_LINUX=.*fips=.*"'  /etc/default/grub; then
	# modify the GRUB command-line if a fips= arg already exists
	sed -i 's/\(^GRUB_CMDLINE_LINUX=".*\)fips=[^[:space:]]*\(.*"\)/\1 fips=1 \2/'  /etc/default/grub
else
	# no existing fips=arg is present, append it
	sed -i 's/\(^GRUB_CMDLINE_LINUX=".*\)"/\1 fips=1"/'  /etc/default/grub
fi

# Get the UUID of the device mounted at /boot.
BOOT_UUID=$(findmnt --noheadings --output uuid --target /boot)

if grep -q '^GRUB_CMDLINE_LINUX=".*boot=.*"'  /etc/default/grub; then
	# modify the GRUB command-line if a boot= arg already exists
	sed -i 's/\(^GRUB_CMDLINE_LINUX=".*\)boot=[^[:space:]]*\(.*"\)/\1 boot=UUID='"${BOOT_UUID} \2/" /etc/default/ grub
else
	# no existing boot=arg is present, append it
	sed -i 's/\(^GRUB_CMDLINE_LINUX=".*\)"/\1 boot=UUID='${BOOT_UUID}'"/'  /etc/default/grub
fi

# Correct the form of kernel command line for each installed kernel in the bootloader
/sbin/grubby --update-kernel=ALL --args="fips=1 boot=UUID=${BOOT_UUID}"
Remediation Anaconda snippet:   (show)


package --add=dracut-fips
Group   Endpoint Protection Software   Group contains 1 group and 1 rule

[ref]   Endpoint protection security software that is not provided or supported by Red Hat can be installed to provide complementary or duplicative security capabilities to those provided by the base platform. Add-on software may not be appropriate for some specialized systems.

Group   McAfee Endpoint Security Software   Group contains 1 rule

[ref]   In DoD environments, McAfee Host-based Security System (HBSS) and VirusScan Enterprise for Linux (VSEL) is required to be installed on all systems.

Rule   Install McAfee Virus Scanning Software   [ref]

Install McAfee VirusScan Enterprise for Linux antivirus software which is provided for DoD systems and uses signatures to search for the presence of viruses on the filesystem.

Warning:  Due to McAfee HIPS being 3rd party software, automated remediation is not available for this configuration check.
Rationale:

Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80127-4

References:  RHEL-07-032000, SV-86837r3_rule, 12, 13, 14, 4, 7, 8, APO01.06, APO13.02, BAI02.01, BAI06.01, DSS04.07, DSS05.01, DSS05.02, DSS05.03, DSS06.06, CCI-000366, CCI-001239, CCI-001668, 4.3.4.3.8, 4.4.3.2, SR 3.2, SR 3.3, SR 3.4, SR 4.1, A.12.2.1, A.14.2.8, A.8.2.3, SC-28, SI-3, SI-3(1)(ii), DE.CM-4, DE.DP-3, PR.DS-1, SRG-OS-000480-GPOS-00227

Group   Software Integrity Checking   Group contains 2 groups and 9 rules

[ref]   Both the AIDE (Advanced Intrusion Detection Environment) software and the RPM package management system provide mechanisms for verifying the integrity of installed software. AIDE uses snapshots of file metadata (such as hashes) and compares these to current system files in order to detect changes.

The RPM package management system can conduct integrity checks by comparing information in its metadata database with files installed on the system.

Group   Verify Integrity with RPM   Group contains 3 rules

[ref]   The RPM package management system includes the ability to verify the integrity of installed packages by comparing the installed files with information about the files taken from the package metadata stored in the RPM database. Although an attacker could corrupt the RPM database (analogous to attacking the AIDE database as described above), this check can still reveal modification of important files. To list which files on the system differ from what is expected by the RPM database:

$ rpm -qVa
See the man page for rpm to see a complete explanation of each column.

Rule   Verify and Correct File Permissions with RPM   [ref]

The RPM package management system can check file access permissions of installed software packages, including many that are important to system security. Verify that the file permissions of system files and commands match vendor values. Check the file permissions with the following command:

$ sudo rpm -Va | awk '{ if (substr($0,2,1)=="M") print $NF }'
Output indicates files that do not match vendor defaults. After locating a file with incorrect permissions, run the following command to determine which package owns it:
$ rpm -qf FILENAME

Next, run the following command to reset its permissions to the correct values:
$ sudo rpm --quiet --setperms PACKAGENAME

Warning:  Note: Due to a bug in the gdm package, the RPM verify command may continue to fail even after file permissions have been correctly set on /var/log/gdm. This is being tracked in Red Hat Bugzilla #1277603.
Rationale:

Permissions on system binaries and configuration files that are too generous could allow an unauthorized user to gain privileges that they should not have. The permissions set by the vendor should be maintained. Any deviations from this baseline should be investigated.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27209-6

References:  RHEL-07-010010, SV-86473r3_rule, 1.2.6, 6.1.3, 6.1.4, 6.1.5, 6.1.6, 6.1.7, 6.1.8, 6.1.9, 6.2.3, 1, 11, 12, 13, 14, 15, 16, 18, 3, 5, 6, 9, 5.10.4.1, APO01.06, APO11.04, BAI03.05, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.04, DSS05.07, DSS06.02, MEA02.01, 3.3.8, 3.4.1, CCI-001494, CCI-001496, 164.308(a)(1)(ii)(D), 164.312(b), 164.312(c)(1), 164.312(c)(2), 164.312(e)(2)(i), 4.3.3.3.9, 4.3.3.5.8, 4.3.3.7.3, 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 2.1, SR 2.10, SR 2.11, SR 2.12, SR 2.8, SR 2.9, SR 5.2, SR 7.6, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.5.1, A.12.6.2, A.12.7.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, AU-9(1), AU-9(3), CM-6(d), CM-6(3), PR.AC-4, PR.DS-5, PR.IP-1, PR.PT-1, Req-11.5, SRG-OS-000257-GPOS-00098, SRG-OS-000278-GPOS-00108

Remediation Shell script:   (show)

Complexity:high
Disruption:medium
Strategy:restrict

# Declare array to hold list of RPM packages we need to correct permissions for
declare -a SETPERMS_RPM_LIST

# Create a list of files on the system having permissions different from what
# is expected by the RPM database
FILES_WITH_INCORRECT_PERMS=($(rpm -Va --nofiledigest | awk '{ if (substr($0,2,1)=="M") print $NF }'))

# For each file path from that list:
# * Determine the RPM package the file path is shipped by,
# * Include it into SETPERMS_RPM_LIST array

for FILE_PATH in "${FILES_WITH_INCORRECT_PERMS[@]}"
do
	RPM_PACKAGE=$(rpm -qf "$FILE_PATH")
	SETPERMS_RPM_LIST=("${SETPERMS_RPM_LIST[@]}" "$RPM_PACKAGE")
done

# Remove duplicate mention of same RPM in $SETPERMS_RPM_LIST (if any)
SETPERMS_RPM_LIST=( $(echo "${SETPERMS_RPM_LIST[@]}" | tr ' ' '\n' | sort -u | tr '\n' ' ') )

# For each of the RPM packages left in the list -- reset its permissions to the
# correct values
for RPM_PACKAGE in "${SETPERMS_RPM_LIST[@]}"
do
	rpm --quiet --setperms "${RPM_PACKAGE}"
done
Remediation Ansible snippet:   (show)

Complexity:high
Disruption:medium
Strategy:restrict
- name: "Read list of files with incorrect permissions"
  shell: "rpm -Va --nofiledigest | awk '{ if (substr($0,2,1)==\"M\") print $NF }'"
  args:
    warn: False # Ignore ANSIBLE0006, we can't fetch files with incorrect permissions using rpm module
  register: files_with_incorrect_permissions
  failed_when: False
  changed_when: False
  check_mode: no
  tags:
    - rpm_verify_permissions
    - high_severity
    - restrict_strategy
    - high_complexity
    - medium_disruption
    - CCE-27209-6
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9(1)
    - NIST-800-53-AU-9(3)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-010010
  

- name: "Correct file permissions with RPM"
  shell: "rpm --quiet --setperms $(rpm -qf '{{ item }}')"
  args:
    warn: False # Ignore ANSIBLE0006, we can't correct permissions using rpm module
  with_items: "{{ files_with_incorrect_permissions.stdout_lines }}"
  when: (files_with_incorrect_permissions.stdout_lines | length > 0) and True
  tags:
    - rpm_verify_permissions
    - high_severity
    - restrict_strategy
    - high_complexity
    - medium_disruption
    - CCE-27209-6
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9(1)
    - NIST-800-53-AU-9(3)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-010010

Rule   Verify and Correct Ownership with RPM   [ref]

The RPM package management system can check file ownership permissions of installed software packages, including many that are important to system security. After locating a file with incorrect permissions, which can be found with

rpm -Va | awk '{ if (substr($0,6,1)=="U" || substr($0,7,1)=="G") print $NF }'
run the following command to determine which package owns it:
$ rpm -qf FILENAME
Next, run the following command to reset its permissions to the correct values:
$ sudo rpm --setugids PACKAGENAME

Warning:  Note: Due to a bug in the gdm package, the RPM verify command may continue to fail even after file permissions have been correctly set on /var/log/gdm. This is being tracked in Red Hat Bugzilla #1277603.
Rationale:

Ownership of binaries and configuration files that is incorrect could allow an unauthorized user to gain privileges that they should not have. The ownership set by the vendor should be maintained. Any deviations from this baseline should be investigated.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80545-7

References:  1.2.6, 6.1.3, 6.1.4, 6.1.5, 6.1.6, 6.1.7, 6.1.8, 6.1.9, 6.2.3, 1, 11, 12, 13, 14, 15, 16, 18, 3, 5, 6, 9, 5.10.4.1, APO01.06, APO11.04, BAI03.05, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.04, DSS05.07, DSS06.02, MEA02.01, 3.3.8, 3.4.1, CCI-001494, CCI-001496, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.7.3, 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 2.1, SR 2.10, SR 2.11, SR 2.12, SR 2.8, SR 2.9, SR 5.2, SR 7.6, A.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.5.1, A.12.6.2, A.12.7.1, A.13.1.1, A.13.1.3, A.13.2.1, A.13.2.3, A.13.2.4, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.6.1.2, A.7.1.1, A.7.1.2, A.7.3.1, A.8.2.2, A.8.2.3, A.9.1.1, A.9.1.2, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-6, AU-9(1), AU-9(3), CM-6(d), CM-6(3), PR.AC-4, PR.DS-5, PR.IP-1, PR.PT-1, Req-11.5, SRG-OS-000257-GPOS-00098, SRG-OS-000278-GPOS-00108

Remediation Shell script:   (show)

Complexity:high
Disruption:medium
Strategy:restrict

# Declare array to hold list of RPM packages we need to correct permissions for
SETPERMS_RPM_LIST=()

# Create a list of files on the system having permissions different from what
# is expected by the RPM database
FILES_WITH_INCORRECT_PERMS=($(rpm -Va --nofiledigest | awk '{ if (substr($0,6,1)=="U" || substr($0,7,1)=="G") print $NF }'))

# For each file path from that list:
# * Determine the RPM package the file path is shipped by,
# * Include it into SETPERMS_RPM_LIST array

for FILE_PATH in "${FILES_WITH_INCORRECT_PERMS[@]}"
do
        RPM_PACKAGE=$(rpm -qf "$FILE_PATH")
	SETPERMS_RPM_LIST+=("$RPM_PACKAGE")
done

# Remove duplicate mention of same RPM in $SETPERMS_RPM_LIST (if any)
SETPERMS_RPM_LIST=( $(printf "%s\n" "${SETPERMS_RPM_LIST[@]}" | sort -u) )

# For each of the RPM packages left in the list -- reset its permissions to the
# correct values
for RPM_PACKAGE in "${SETPERMS_RPM_LIST[@]}"
do
        rpm --setugids "${RPM_PACKAGE}"
done
Remediation Ansible snippet:   (show)

Complexity:high
Disruption:medium
Strategy:restrict
- name: "Read list of files with incorrect ownership"
  shell: "rpm -Va --nofiledigest | awk '{ if (substr($0,6,1)==\"U\" || substr($0,7,1)==\"G\") print $NF }'"
  args:
    warn: False # Ignore ANSIBLE0006, we can't fetch files with incorrect ownership using rpm module
  register: files_with_incorrect_ownership
  failed_when: False
  changed_when: False
  check_mode: no
  tags:
    - rpm_verify_ownership
    - high_severity
    - restrict_strategy
    - high_complexity
    - medium_disruption
    - CCE-80545-7
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9(1)
    - NIST-800-53-AU-9(3)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
  

- name: Create list of uniq packages
  shell: "rpm -qf {{ files_with_incorrect_ownership.stdout_lines }}|sort |uniq"
  args:
    warn: False # Ignore ANSIBLE0006, we can't fetch packages with files with incorrect ownership using rpm module
  register: uniq_list_of_packages
  when: (files_with_incorrect_ownership.stdout_lines | length > 0) and True
  tags:
    - rpm_verify_ownership
    - high_severity
    - restrict_strategy
    - high_complexity
    - medium_disruption
    - CCE-80545-7
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9(1)
    - NIST-800-53-AU-9(3)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1

- name: "Correct file ownership with RPM"
  shell: "rpm --quiet --setugids '{{ item }}'"
  args:
    warn: False # Ignore ANSIBLE0006, we can't correct ownership using rpm module
  with_items: "{{ uniq_list_of_packages.stdout_lines }}"
  when: (files_with_incorrect_ownership.stdout_lines | length > 0) and True
  tags:
    - rpm_verify_ownership
    - high_severity
    - restrict_strategy
    - high_complexity
    - medium_disruption
    - CCE-80545-7
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9(1)
    - NIST-800-53-AU-9(3)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1

Rule   Verify File Hashes with RPM   [ref]

Without cryptographic integrity protections, system executables and files can be altered by unauthorized users without detection. The RPM package management system can check the hashes of installed software packages, including many that are important to system security. To verify that the cryptographic hash of system files and commands match vendor values, run the following command to list which files on the system have hashes that differ from what is expected by the RPM database:

$ rpm -Va | grep '^..5'
A "c" in the second column indicates that a file is a configuration file, which may appropriately be expected to change. If the file was not expected to change, investigate the cause of the change using audit logs or other means. The package can then be reinstalled to restore the file. Run the following command to determine which package owns the file:
$ rpm -qf FILENAME
The package can be reinstalled from a yum repository using the command:
$ sudo yum reinstall PACKAGENAME
Alternatively, the package can be reinstalled from trusted media using the command:
$ sudo rpm -Uvh PACKAGENAME

Rationale:

The hashes of important files like system executables should match the information given by the RPM database. Executables with erroneous hashes could be a sign of nefarious activity on the system.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27157-7

References:  RHEL-07-010020, SV-86479r3_rule, 1.2.6, 11, 2, 3, 9, 5.10.4.1, APO01.06, BAI03.05, BAI06.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS06.02, 3.3.8, 3.4.1, CCI-000663, 164.308(a)(1)(ii)(D), 164.312(b), 164.312(c)(1), 164.312(c)(2), 164.312(e)(2)(i), 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, SR 7.6, A.11.2.4, A.12.1.2, A.12.2.1, A.12.5.1, A.12.6.2, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, CM-6(d), CM-6(3), SI-7(1), PR.DS-6, PR.DS-8, PR.IP-1, Req-11.5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)


# Find which files have incorrect hash (not in /etc, because there are all system related config. files) and then get files names
files_with_incorrect_hash="$(rpm -Va | grep -E '^..5.* /(bin|sbin|lib|lib64|usr)/' | awk '{print $NF}' )"
# From files names get package names and change newline to space, because rpm writes each package to new line
packages_to_reinstall="$(rpm -qf $files_with_incorrect_hash | tr '\n' ' ')"

yum reinstall -y $packages_to_reinstall
Remediation Ansible snippet:   (show)

Complexity:high
Disruption:medium
- name: "Set fact: Package manager reinstall command (dnf)"
  set_fact:
    package_manager_reinstall_cmd: dnf reinstall -y
  when: ansible_distribution == "Fedora" and True
  tags:
    - rpm_verify_hashes
    - high_severity
    - unknown_strategy
    - high_complexity
    - medium_disruption
    - CCE-27157-7
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SI-7(1)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-010020

- name: "Set fact: Package manager reinstall command (yum)"
  set_fact:
    package_manager_reinstall_cmd: yum reinstall -y
  when: (ansible_distribution == "RedHat" or ansible_distribution == "OracleLinux") and True
  tags:
    - rpm_verify_hashes
    - high_severity
    - unknown_strategy
    - high_complexity
    - medium_disruption
    - CCE-27157-7
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SI-7(1)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-010020

- name: "Read files with incorrect hash"
  shell: "rpm -Va | grep -E '^..5.* /(bin|sbin|lib|lib64|usr)/' | awk '{print $NF}'"
  args:
    warn: False # Ignore ANSIBLE0006, we can't fetch files with incorrect hash using rpm module
  register: files_with_incorrect_hash
  changed_when: False
  when: (package_manager_reinstall_cmd is defined) and True
  check_mode: no
  tags:
    - rpm_verify_hashes
    - high_severity
    - unknown_strategy
    - high_complexity
    - medium_disruption
    - CCE-27157-7
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SI-7(1)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-010020

- name: "Reinstall packages of files with incorrect hash"
  shell: "{{ package_manager_reinstall_cmd }} $(rpm -qf '{{ item }}')"
  args:
    warn: False # Ignore ANSIBLE0006, this task is flexible with regards to package manager
  with_items: "{{ files_with_incorrect_hash.stdout_lines }}"
  when: (package_manager_reinstall_cmd is defined and (files_with_incorrect_hash.stdout_lines | length > 0)) and True
  tags:
    - rpm_verify_hashes
    - high_severity
    - unknown_strategy
    - high_complexity
    - medium_disruption
    - CCE-27157-7
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SI-7(1)
    - NIST-800-171-3.3.8
    - NIST-800-171-3.4.1
    - PCI-DSS-Req-11.5
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-010020
Group   Verify Integrity with AIDE   Group contains 6 rules

[ref]   AIDE conducts integrity checks by comparing information about files with previously-gathered information. Ideally, the AIDE database is created immediately after initial system configuration, and then again after any software update. AIDE is highly configurable, with further configuration information located in /usr/share/doc/aide-VERSION.

Rule   Install AIDE   [ref]

The aide package can be installed with the following command:

$ sudo yum install aide

Rationale:

The AIDE package must be installed if it is to be available for integrity checking.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27096-7

References:  1.3.1, 1, 11, 12, 13, 14, 15, 16, 2, 3, 5, 7, 8, 9, 5.10.1.3, APO01.06, BAI01.06, BAI02.01, BAI03.05, BAI06.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS03.05, DSS04.07, DSS05.02, DSS05.03, DSS05.05, DSS05.07, DSS06.02, DSS06.06, 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, SR 4.1, SR 6.2, SR 7.6, A.11.2.4, A.12.1.2, A.12.2.1, A.12.4.1, A.12.5.1, A.12.6.2, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.14.2.7, A.15.2.1, A.8.2.3, CM-3(d), CM-3(e), CM-6(d), CM-6(3), SC-28, SI-7, DE.CM-1, DE.CM-7, PR.DS-1, PR.DS-6, PR.DS-8, PR.IP-1, PR.IP-3, Req-11.5

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable
# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install aide
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: Ensure aide is installed
  package:
    name: aide
    state: present
  tags:
    - package_aide_installed
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
    - CCE-27096-7
    - NIST-800-53-CM-3(d)
    - NIST-800-53-CM-3(e)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SC-28
    - NIST-800-53-SI-7
    - PCI-DSS-Req-11.5
    - CJIS-5.10.1.3
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
include install_aide

class install_aide {
  package { 'aide':
    ensure => 'installed',
  }
}
Remediation Anaconda snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable

package --add=aide

Rule   Configure AIDE to Verify Extended Attributes   [ref]

By default, the xattrs option is added to the FIPSR ruleset in AIDE. If using a custom ruleset or the xattrs option is missing, add xattrs to the appropriate ruleset. For example, add xattrs to the following line in /etc/aide.conf:

FIPSR = p+i+n+u+g+s+m+c+acl+selinux+xattrs+sha256
AIDE rules can be configured in multiple ways; this is merely one example that is already configured by default.

Rationale:

Extended attributes in file systems are used to contain arbitrary data and file metadata with security implications.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80376-7

References:  RHEL-07-021610, SV-86695r3_rule, 2, 3, APO01.06, BAI03.05, BAI06.01, DSS06.02, CCI-000366, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, A.11.2.4, A.12.2.1, A.12.5.1, A.14.1.2, A.14.1.3, A.14.2.4, SI-7.1, PR.DS-6, PR.DS-8, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install aide

aide_conf="/etc/aide.conf"

groups=$(LC_ALL=C grep "^[A-Z]\+" $aide_conf | grep -v "^ALLXTRAHASHES" | cut -f1 -d '=' | tr -d ' ' | sort -u)

for group in $groups
do
	config=$(grep "^$group\s*=" $aide_conf | cut -f2 -d '=' | tr -d ' ')

	if ! [[ $config = *xattrs* ]]
	then
		if [[ -z $config ]]
		then
			config="xattrs"
		else
			config=$config"+xattrs"
		fi
	fi
	sed -i "s/^$group\s*=.*/$group = $config/g" $aide_conf
done

Rule   Configure AIDE to Verify Access Control Lists (ACLs)   [ref]

By default, the acl option is added to the FIPSR ruleset in AIDE. If using a custom ruleset or the acl option is missing, add acl to the appropriate ruleset. For example, add acl to the following line in /etc/aide.conf:

FIPSR = p+i+n+u+g+s+m+c+acl+selinux+xattrs+sha256
AIDE rules can be configured in multiple ways; this is merely one example that is already configured by default.

Rationale:

ACLs can provide permissions beyond those permitted through the file mode and must be verified by the file integrity tools.

Severity: 
low
Identifiers and References

Identifiers:  CCE-80375-9

References:  RHEL-07-021600, SV-86693r3_rule, 2, 3, APO01.06, BAI03.05, BAI06.01, DSS06.02, CCI-000366, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, A.11.2.4, A.12.2.1, A.12.5.1, A.14.1.2, A.14.1.3, A.14.2.4, SI-7.1, PR.DS-6, PR.DS-8, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install aide

aide_conf="/etc/aide.conf"

groups=$(LC_ALL=C grep "^[A-Z]\+" $aide_conf | grep -v "^ALLXTRAHASHES" | cut -f1 -d '=' | tr -d ' ' | sort -u)

for group in $groups
do
	config=$(grep "^$group\s*=" $aide_conf | cut -f2 -d '=' | tr -d ' ')

	if ! [[ $config = *acl* ]]
	then
		if [[ -z $config ]]
		then
			config="acl"
		else
			config=$config"+acl"
		fi
	fi
	sed -i "s/^$group\s*=.*/$group = $config/g" $aide_conf
done

Rule   Configure AIDE to Use FIPS 140-2 for Validating Hashes   [ref]

By default, the sha512 option is added to the NORMAL ruleset in AIDE. If using a custom ruleset or the sha512 option is missing, add sha512 to the appropriate ruleset. For example, add sha512 to the following line in /etc/aide.conf:

NORMAL = FIPSR+sha512
AIDE rules can be configured in multiple ways; this is merely one example that is already configured by default.

Rationale:

File integrity tools use cryptographic hashes for verifying file contents and directories have not been altered. These hashes must be FIPS 140-2 approved cryptographic hashes.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80377-5

References:  RHEL-07-021620, SV-86697r3_rule, 2, 3, APO01.06, BAI03.05, BAI06.01, DSS06.02, 3.13.11, CCI-000366, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, A.11.2.4, A.12.2.1, A.12.5.1, A.14.1.2, A.14.1.3, A.14.2.4, SI-7(1), PR.DS-6, PR.DS-8, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install aide

aide_conf="/etc/aide.conf"
forbidden_hashes=(sha1 rmd160 sha256 whirlpool tiger haval gost crc32)

groups=$(LC_ALL=C grep "^[A-Z]\+" $aide_conf | cut -f1 -d ' ' | tr -d ' ' | sort -u)

for group in $groups
do
	config=$(grep "^$group\s*=" $aide_conf | cut -f2 -d '=' | tr -d ' ')

	if ! [[ $config = *sha512* ]]
	then
		config=$config"+sha512"
	fi

	for hash in ${forbidden_hashes[@]}
	do
		config=$(echo $config | sed "s/$hash//")
	done

	config=$(echo $config | sed "s/^\+*//")
	config=$(echo $config | sed "s/\+\++/+/")
	config=$(echo $config | sed "s/\+$//")

	sed -i "s/^$group\s*=.*/$group = $config/g" $aide_conf
done

Rule   Configure Notification of Post-AIDE Scan Details   [ref]

AIDE should notify appropriate personnel of the details of a scan after the scan has been run. If AIDE has already been configured for periodic execution in /etc/crontab, append the following line to the existing AIDE line:

 | /bin/mail -s "$(hostname) - AIDE Integrity Check" root@localhost
Otherwise, add the following line to /etc/crontab:
05 4 * * * root /usr/sbin/aide --check | /bin/mail -s "$(hostname) - AIDE Integrity Check" root@localhost
AIDE can be executed periodically through other means; this is merely one example.

Rationale:

Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security.

Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's Information Management Officer (IMO)/Information System Security Officer (ISSO) and System Administrators (SAs) must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80374-2

References:  RHEL-07-020040, SV-86599r2_rule, 1, 11, 12, 13, 15, 16, 2, 3, 5, 7, 8, 9, BAI01.06, BAI06.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS03.05, DSS05.02, DSS05.05, DSS05.07, CCI-001744, 4.3.4.3.2, 4.3.4.3.3, SR 6.2, SR 7.6, A.12.1.2, A.12.4.1, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, A.14.2.7, A.15.2.1, CM-3(5), DE.CM-1, DE.CM-7, PR.IP-1, PR.IP-3, SRG-OS-000363-GPOS-00150

Remediation Shell script:   (show)

# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install aide

CRONTAB=/etc/crontab
CRONDIRS='/etc/cron.d /etc/cron.daily /etc/cron.weekly /etc/cron.monthly'

if [ -f /var/spool/cron/root ]; then
	VARSPOOL=/var/spool/cron/root
fi

if ! grep -qR '^.*\/usr\/sbin\/aide\s*\-\-check.*|.*\/bin\/mail\s*-s\s*".*"\s*root@.*$' $CRONTAB $VARSPOOL $CRONDIRS; then
	echo '0 5 * * * root /usr/sbin/aide  --check | /bin/mail -s "$(hostname) - AIDE Integrity Check" root@localhost' >> $CRONTAB
fi

Rule   Configure Periodic Execution of AIDE   [ref]

At a minimum, AIDE should be configured to run a weekly scan. At most, AIDE should be run daily. To implement a daily execution of AIDE at 4:05am using cron, add the following line to /etc/crontab:

05 4 * * * root /usr/sbin/aide --check
To implement a weekly execution of AIDE at 4:05am using cron, add the following line to /etc/crontab:
05 4 * * 0 root /usr/sbin/aide --check
AIDE can be executed periodically through other means; this is merely one example. The usage of cron's special time codes, such as @daily and @weekly is acceptable.

Rationale:

By default, AIDE does not install itself for periodic execution. Periodically running AIDE is necessary to reveal unexpected changes in installed files.

Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security.

Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's Information Management Officer (IMO)/Information System Security Officer (ISSO) and System Administrators (SAs) must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-26952-2

References:  RHEL-07-020030, SV-86597r2_rule, 1.3.2, 1, 11, 12, 13, 14, 15, 16, 2, 3, 5, 7, 8, 9, 5.10.1.3, APO01.06, BAI01.06, BAI02.01, BAI03.05, BAI06.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS01.03, DSS03.05, DSS04.07, DSS05.02, DSS05.03, DSS05.05, DSS05.07, DSS06.02, DSS06.06, CCI-001744, 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, SR 4.1, SR 6.2, SR 7.6, A.11.2.4, A.12.1.2, A.12.2.1, A.12.4.1, A.12.5.1, A.12.6.2, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, A.14.2.7, A.15.2.1, A.8.2.3, CM-3(d), CM-3(e), CM-3(5), CM-6(d), CM-6(3), SC-28, SI-7, DE.CM-1, DE.CM-7, PR.DS-1, PR.DS-6, PR.DS-8, PR.IP-1, PR.IP-3, Req-11.5, SRG-OS-000363-GPOS-00150

Remediation Shell script:   (show)

# Function to install packages on RHEL, Fedora, Debian, and possibly other systems.
#
# Example Call(s):
#
#     package_install aide
#
function package_install {

# Load function arguments into local variables
local package="$1"

# Check sanity of the input
if [ $# -ne "1" ]
then
  echo "Usage: package_install 'package_name'"
  echo "Aborting."
  exit 1
fi

if which dnf ; then
  if ! rpm -q --quiet "$package"; then
    dnf install -y "$package"
  fi
elif which yum ; then
  if ! rpm -q --quiet "$package"; then
    yum install -y "$package"
  fi
elif which apt-get ; then
  apt-get install -y "$package"
else
  echo "Failed to detect available packaging system, tried dnf, yum and apt-get!"
  echo "Aborting."
  exit 1
fi

}

package_install aide

if ! grep -q "/usr/sbin/aide --check" /etc/crontab ; then
    echo "05 4 * * * root /usr/sbin/aide --check" >> /etc/crontab
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Ensure AIDE is installed"
  package:
    name: "{{ item }}"
    state: present
  with_items:
    - aide
  tags:
    - aide_periodic_cron_checking
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-26952-2
    - NIST-800-53-CM-3(d)
    - NIST-800-53-CM-3(e)
    - NIST-800-53-CM-3(5)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SC-28
    - NIST-800-53-SI-7
    - PCI-DSS-Req-11.5
    - CJIS-5.10.1.3
    - DISA-STIG-RHEL-07-020030
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Configure Periodic Execution of AIDE"
  cron:
    name: "run AIDE check"
    minute: 05
    hour: 04
    weekday: 0
    user: root
    job: "/usr/sbin/aide --check"
  tags:
    - aide_periodic_cron_checking
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-26952-2
    - NIST-800-53-CM-3(d)
    - NIST-800-53-CM-3(e)
    - NIST-800-53-CM-3(5)
    - NIST-800-53-CM-6(d)
    - NIST-800-53-CM-6(3)
    - NIST-800-53-SC-28
    - NIST-800-53-SI-7
    - PCI-DSS-Req-11.5
    - CJIS-5.10.1.3
    - DISA-STIG-RHEL-07-020030
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Group   Updating Software   Group contains 4 rules

[ref]   The yum command line tool is used to install and update software packages. The system also provides a graphical software update tool in the System menu, in the Administration submenu, called Software Update.

Red Hat Enterprise Linux 7 systems contain an installed software catalog called the RPM database, which records metadata of installed packages. Consistently using yum or the graphical Software Update for all software installation allows for insight into the current inventory of installed software on the system.

Rule   Ensure Software Patches Installed   [ref]

If the system is joined to the Red Hat Network, a Red Hat Satellite Server, or a yum server, run the following command to install updates:

$ sudo yum update
If the system is not configured to use one of these sources, updates (in the form of RPM packages) can be manually downloaded from the Red Hat Network and installed using rpm.

NOTE: U.S. Defense systems are required to be patched within 30 days or sooner as local policy dictates.

Rationale:

Installing software updates is a fundamental mitigation against the exploitation of publicly-known vulnerabilities. If the most recent security patches and updates are not installed, unauthorized users may take advantage of weaknesses in the unpatched software. The lack of prompt attention to patching could result in a system compromise.

Severity: 
high
Identifiers and References

Identifiers:  CCE-26895-3

References:  RHEL-07-020260, SV-86623r4_rule, 1.8, 18, 20, 4, 5.10.4.1, APO12.01, APO12.02, APO12.03, APO12.04, BAI03.10, DSS05.01, DSS05.02, CCI-000366, 4.2.3, 4.2.3.12, 4.2.3.7, 4.2.3.9, A.12.6.1, A.14.2.3, A.16.1.3, A.18.2.2, A.18.2.3, SI-2, SI-2(c), MA-1(b), ID.RA-1, PR.IP-12, FMT_MOF_EXT.1, Req-6.2, SRG-OS-000480-GPOS-00227, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

Complexity:low
Disruption:high
Reboot:true
Strategy:patch
yum -y update
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:high
Reboot:true
Strategy:patch
- name: "Security patches are up to date"
  package:
    name: "*"
    state: "latest"
  tags:
    - skip_ansible_lint # [ANSIBLE0010] Skipping lint because ANSIBLE0010 is a bad security practice
    - security_patches_up_to_date
    - high_severity
    - patch_strategy
    - low_complexity
    - high_disruption
    - CCE-26895-3
    - NIST-800-53-SI-2
    - NIST-800-53-SI-2(c)
    - NIST-800-53-MA-1(b)
    - PCI-DSS-Req-6.2
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-020260
  

Rule   Ensure gpgcheck Enabled for Local Packages   [ref]

yum should be configured to verify the signature(s) of local packages prior to installation. To configure yum to verify signatures of local packages, set the localpkg_gpgcheck to 1 in /etc/yum.conf.

Rationale:

Changes to any software components can have significant effects to the overall security of the operating system. This requirement ensures the software has not been tampered and has been provided by a trusted vendor.

Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80347-8

References:  RHEL-07-020060, SV-86603r2_rule, 11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.4.8, CCI-001749, 164.308(a)(1)(ii)(D), 164.312(b), 164.312(c)(1), 164.312(c)(2), 164.312(e)(2)(i), 4.3.4.3.2, 4.3.4.3.3, SR 7.6, A.12.1.2, A.12.5.1, A.12.6.2, A.14.2.2, A.14.2.3, A.14.2.4, CM-5(3), CM-11, PR.IP-1, FAU_GEN.1.1.c, SRG-OS-000366-GPOS-00153, SRG-OS-000366-VMM-001430, SRG-OS-000370-VMM-001460, SRG-OS-000404-VMM-001650

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append '/etc/yum.conf' '^localpkg_gpgcheck' '1' 'CCE-80347-8'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: Check existence of yum on Fedora
  stat:
    path: /etc/yum.conf
  register: yum_config_file
  check_mode: no
  when: ansible_distribution == "Fedora"

# Old versions of Fedora use yum

- name: Ensure GPG check Enabled for Local Packages (Yum)
  ini_file:
    dest: /etc/yum.conf
    section: main
    option: localpkg_gpgcheck
    value: 1
    create: True
  when: (ansible_distribution == "RedHat" or ansible_distribution == "CentOS" or yum_config_file.stat.exists) and True
  tags:
    - ensure_gpgcheck_local_packages
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80347-8
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11
    - NIST-800-171-3.4.8
    - DISA-STIG-RHEL-07-020060

- name: Ensure GPG check Enabled for Local Packages (DNF)
  ini_file:
    dest: /etc/dnf/dnf.conf
    section: main
    option: localpkg_gpgcheck
    value: 1
    create: True
  when: ansible_distribution == "Fedora" and True
  tags:
    - ensure_gpgcheck_local_packages
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80347-8
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11
    - NIST-800-171-3.4.8
    - DISA-STIG-RHEL-07-020060

Rule   Ensure yum Removes Previous Package Versions   [ref]

yum should be configured to remove previous software components after new versions have been installed. To configure yum to remove the previous software components after updating, set the clean_requirements_on_remove to 1 in /etc/yum.conf.

Rationale:

Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by some adversaries.

Severity: 
low
Identifiers and References

Identifiers:  CCE-80346-0

References:  RHEL-07-020200, SV-86611r2_rule, 18, 20, 4, APO12.01, APO12.02, APO12.03, APO12.04, BAI03.10, DSS05.01, DSS05.02, 3.4.8, CCI-002617, 4.2.3, 4.2.3.12, 4.2.3.7, 4.2.3.9, A.12.6.1, A.14.2.3, A.16.1.3, A.18.2.2, A.18.2.3, SI-2(6), CM-11, ID.RA-1, PR.IP-12, SRG-OS-000437-GPOS-00194

Remediation Shell script:   (show)


if grep --silent ^clean_requirements_on_remove /etc/yum.conf ; then
        sed -i "s/^clean_requirements_on_remove.*/clean_requirements_on_remove=1/g" /etc/yum.conf
else
        echo -e "\n# Set clean_requirements_on_remove to 1 per security requirements" >> /etc/yum.conf
        echo "clean_requirements_on_remove=1" >> /etc/yum.conf
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: "Ensure YUM Removes Previous Package Versions"
  lineinfile:
      dest: /etc/yum.conf
      regexp: ^#?clean_requirements_on_remove
      line: clean_requirements_on_remove=1
      insertafter: '\[main\]'
  tags:
    - clean_components_post_updating
    - low_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-80346-0
    - NIST-800-53-SI-2(6)
    - NIST-800-53-CM-11
    - NIST-800-171-3.4.8
    - DISA-STIG-RHEL-07-020200
  

Rule   Ensure gpgcheck Enabled In Main yum Configuration   [ref]

The gpgcheck option controls whether RPM packages' signatures are always checked prior to installation. To configure yum to check package signatures before installing them, ensure the following line appears in /etc/yum.conf in the [main] section:

gpgcheck=1

Rationale:

Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor.
Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization.
Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. Certificates used to verify the software must be from an approved Certificate Authority (CA).

Severity: 
high
Identifiers and References

Identifiers:  CCE-26989-4

References:  RHEL-07-020050, SV-86601r2_rule, 1.2.2, 11, 2, 3, 9, 5.10.4.1, APO01.06, BAI03.05, BAI06.01, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS06.02, 3.4.8, CCI-001749, 164.308(a)(1)(ii)(D), 164.312(b), 164.312(c)(1), 164.312(c)(2), 164.312(e)(2)(i), 4.3.4.3.2, 4.3.4.3.3, 4.3.4.4.4, SR 3.1, SR 3.3, SR 3.4, SR 3.8, SR 7.6, A.11.2.4, A.12.1.2, A.12.2.1, A.12.5.1, A.12.6.2, A.14.1.2, A.14.1.3, A.14.2.2, A.14.2.3, A.14.2.4, CM-5(3), CM-11, SI-7, MA-1(b), PR.DS-6, PR.DS-8, PR.IP-1, FAU_GEN.1.1.c, Req-6.2, SRG-OS-000366-GPOS-00153, SRG-OS-000366-VMM-001430, SRG-OS-000370-VMM-001460, SRG-OS-000404-VMM-001650

Remediation Shell script:   (show)

# Function to replace configuration setting in config file or add the configuration setting if
# it does not exist.
#
# Expects arguments:
#
# config_file:		Configuration file that will be modified
# key:			Configuration option to change
# value:		Value of the configuration option to change
# cce:			The CCE identifier or '@CCENUM@' if no CCE identifier exists
# format:		The printf-like format string that will be given stripped key and value as arguments,
#			so e.g. '%s=%s' will result in key=value subsitution (i.e. without spaces around =)
#
# Optional arugments:
#
# format:		Optional argument to specify the format of how key/value should be
# 			modified/appended in the configuration file. The default is key = value.
#
# Example Call(s):
#
#     With default format of 'key = value':
#     replace_or_append '/etc/sysctl.conf' '^kernel.randomize_va_space' '2' '@CCENUM@'
#
#     With custom key/value format:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' 'disabled' '@CCENUM@' '%s=%s'
#
#     With a variable:
#     replace_or_append '/etc/sysconfig/selinux' '^SELINUX=' $var_selinux_state '@CCENUM@' '%s=%s'
#
function replace_or_append {
  local default_format='%s = %s' case_insensitive_mode=yes sed_case_insensitive_option='' grep_case_insensitive_option=''
  local config_file=$1
  local key=$2
  local value=$3
  local cce=$4
  local format=$5

  if [ "$case_insensitive_mode" = yes ]; then
    sed_case_insensitive_option="i"
    grep_case_insensitive_option="-i"
  fi
  [ -n "$format" ] || format="$default_format"
  # Check sanity of the input
  [ $# -ge "3" ] || { echo "Usage: replace_or_append <config_file_location> <key_to_search> <new_value> [<CCE number or literal '@CCENUM@' if unknown>] [printf-like format, default is '$default_format']" >&2; exit 1; }

  # Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
  # Otherwise, regular sed command will do.
  sed_command=('sed' '-i')
  if test -L "$config_file"; then
    sed_command+=('--follow-symlinks')
  fi

  # Test that the cce arg is not empty or does not equal @CCENUM@.
  # If @CCENUM@ exists, it means that there is no CCE assigned.
  if [ -n "$cce" ] && [ "$cce" != '@CCENUM@' ]; then
    cce="CCE-${cce}"
  else
    cce="CCE"
  fi

  # Strip any search characters in the key arg so that the key can be replaced without
  # adding any search characters to the config file.
  stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "$key")

  # shellcheck disable=SC2059
  printf -v formatted_output "$format" "$stripped_key" "$value"

  # If the key exists, change it. Otherwise, add it to the config_file.
  # We search for the key string followed by a word boundary (matched by \>),
  # so if we search for 'setting', 'setting2' won't match.
  if LC_ALL=C grep -q -m 1 $grep_case_insensitive_option -e "${key}\\>" "$config_file"; then
    "${sed_command[@]}" "s/${key}\\>.*/$formatted_output/g$sed_case_insensitive_option" "$config_file"
  else
    # \n is precaution for case where file ends without trailing newline
    printf '\n# Per %s: Set %s in %s\n' "$cce" "$formatted_output" "$config_file" >> "$config_file"
    printf '%s\n' "$formatted_output" >> "$config_file"
  fi
}

replace_or_append "/etc/yum.conf" '^gpgcheck' '1' 'CCE-26989-4'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: Check existence of yum on Fedora
  stat:
    path: /etc/yum.conf
  register: yum_config_file
  check_mode: no
  when: ansible_distribution == "Fedora"

# Old versions of Fedora use yum

- name: Ensure GPG check is globally activated (yum)
  ini_file:
    dest: /etc/yum.conf
    section: main
    option: gpgcheck
    value: 1
    create: False
  when: (ansible_distribution == "RedHat" or ansible_distribution == "CentOS" or yum_config_file.stat.exists) and True
  tags:
    - ensure_gpgcheck_globally_activated
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-26989-4
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11
    - NIST-800-53-SI-7
    - NIST-800-53-MA-1(b)
    - NIST-800-171-3.4.8
    - PCI-DSS-Req-6.2
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-020050

- name: Ensure GPG check is globally activated (dnf)
  ini_file:
    dest: /etc/dnf/dnf.conf
    section: main
    option: gpgcheck
    value: 1
    create: False
  when: ansible_distribution == "Fedora" and True
  tags:
    - ensure_gpgcheck_globally_activated
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-26989-4
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11
    - NIST-800-53-SI-7
    - NIST-800-53-MA-1(b)
    - NIST-800-171-3.4.8
    - PCI-DSS-Req-6.2
    - CJIS-5.10.4.1
    - DISA-STIG-RHEL-07-020050
Group   GNOME Desktop Environment   Group contains 2 groups and 12 rules

[ref]   GNOME is a graphical desktop environment bundled with many Linux distributions that allow users to easily interact with the operating system graphically rather than textually. The GNOME Graphical Display Manager (GDM) provides login, logout, and user switching contexts as well as display server management.

GNOME is developed by the GNOME Project and is considered the default Red Hat Graphical environment.

For more information on GNOME and the GNOME Project, see https://www.gnome.org.

Group   Configure GNOME Screen Locking   Group contains 8 rules

[ref]   In the default GNOME3 desktop, the screen can be locked by selecting the user name in the far right corner of the main panel and selecting Lock.

The following sections detail commands to enforce idle activation of the screensaver, screen locking, a blank-screen screensaver, and an idle activation time.

Because users should be trained to lock the screen when they step away from the computer, the automatic locking feature is only meant as a backup.

The root account can be screen-locked; however, the root account should never be used to log into an X Windows environment and should only be used to for direct login via console in emergency circumstances.

For more information about enforcing preferences in the GNOME3 environment using the DConf configuration system, see http://wiki.gnome.org/dconf and the man page dconf(1). For Red Hat specific information on configuring DConf settings, see https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Desktop_Migration_and_Administration_Guide/part-Configuration_and_Administration.html

Rule   Ensure Users Cannot Change GNOME3 Session Idle Settings   [ref]

If not already configured, ensure that users cannot change GNOME3 session idle settings by adding /org/gnome/desktop/session/idle-delay to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:

/org/gnome/desktop/session/idle-delay
After the settings have been set, run dconf update.

Warning:  When selecting this rule in a profile, make sure that rule with ID dconf_use_text_backend is selected as well: dconf-related rules can't be checked by OVAL if dconf is using a binary database as it's data backend. dconf has to be forced to use config files directly as backend, as those config files are checked by OVAL probes.
Rationale:

A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80544-0

References:  RHEL-07-010082, SV-87809r4_rule, 1, 12, 15, 16, DSS05.04, DSS05.10, DSS06.10, 3.1.10, CCI-000057, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-11(a), PR.AC-7, FMT_MOF_EXT.1, SRG-OS-00029-GPOS-0010

Remediation Shell script:   (show)

function include_dconf_settings {
	:
}

# Function to configure DConf settings for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_settings 'org/gnome/login-screen' 'banner-message-enable' 'true' 'local.d' '10-banner'
#
function dconf_settings {
	local _path=$1 _key=$2 _value=$3 _db=$4 _settingFile=$5

	# Check sanity of the input
	if [ $# -ne "5" ]
	then
		echo "Usage: dconf_settings 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_settingsfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	SETTINGSFILES=($(grep -r "\[${_path}]" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1))
	DCONFFILE="/etc/dconf/db/${_db}/${_settingFile}"
	DBDIR="/etc/dconf/db/${_db}"

	mkdir -p "${DBDIR}"

	if [[ -z "${SETTINGSFILES[@]}" ]]
	then
		[ ! -z ${DCONFFILE} ] || $(echo "" >> ${DCONFFILE})
		echo "[${_path}]" >> ${DCONFFILE}
		echo "${_key}=${_value}" >> ${DCONFFILE}
	else
		if grep -q "^(?!#)${_key}" ${SETTINGSFILES[@]}
		then
			sed -i "s/${_key}\s*=\s*.*/${_key}=${_value}/g" ${SETTINGSFILES[@]}
		else
			sed -i "\|\[${_path}]|a\\${_key}=${_value}" ${SETTINGSFILES[@]}
		fi
	fi

	dconf update
}

# Function to configure DConf locks for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_lock 'org/gnome/login-screen' 'banner-message-enable' 'local.d' 'banner'
#
function dconf_lock {
	local _key=$1 _setting=$2 _db=$3 _lockFile=$4

	# Check sanity of the input
	if [ $# -ne "4" ]
	then
		echo "Usage: dconf_lock 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_lockfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	LOCKFILES=$(grep -r "^/${_key}/${_setting}$" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1)
	LOCKSFOLDER="/etc/dconf/db/${_db}/locks"

	mkdir -p "${LOCKSFOLDER}"

	if [[ -z "${LOCKFILES}" ]]
	then
		echo "/${_key}/${_setting}" >> "/etc/dconf/db/${_db}/locks/${_lockFile}"
	fi
}


include_dconf_settings

dconf_lock 'org/gnome/desktop/session' 'idle-delay' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium

- name: "Prevent user modification of GNOME Session idle-delay"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/desktop/session/idle-delay'
    line: '/org/gnome/desktop/session/idle-delay'
    create: yes
  tags:
    - dconf_gnome_session_idle_user_locks
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80544-0
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - DISA-STIG-RHEL-07-010082
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Set GNOME3 Screensaver Lock Delay After Activation Period   [ref]

To activate the locking delay of the screensaver in the GNOME3 desktop when the screensaver is activated, add or set lock-delay to uint32 5 in /etc/dconf/db/local.d/00-security-settings. For example:

[org/gnome/desktop/screensaver]
lock-delay=uint32 5
Once the setting has been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:
/org/gnome/desktop/screensaver/lock-delay
After the settings have been set, run dconf update.

Warning:  When selecting this rule in a profile, make sure that rule with ID dconf_use_text_backend is selected as well: dconf-related rules can't be checked by OVAL if dconf is using a binary database as it's data backend. dconf has to be forced to use config files directly as backend, as those config files are checked by OVAL probes.
Rationale:

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absense.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80370-0

References:  RHEL-07-010110, SV-86525r3_rule, 1, 12, 15, 16, DSS05.04, DSS05.10, DSS06.10, 3.1.10, CCI-000056, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-11(a), PR.AC-7, FMT_MOF_EXT.1, Req-8.1.8, OS-SRG-000029-GPOS-00010

Remediation Shell script:   (show)


var_screensaver_lock_delay="5"
function include_dconf_settings {
	:
}

# Function to configure DConf settings for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_settings 'org/gnome/login-screen' 'banner-message-enable' 'true' 'local.d' '10-banner'
#
function dconf_settings {
	local _path=$1 _key=$2 _value=$3 _db=$4 _settingFile=$5

	# Check sanity of the input
	if [ $# -ne "5" ]
	then
		echo "Usage: dconf_settings 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_settingsfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	SETTINGSFILES=($(grep -r "\[${_path}]" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1))
	DCONFFILE="/etc/dconf/db/${_db}/${_settingFile}"
	DBDIR="/etc/dconf/db/${_db}"

	mkdir -p "${DBDIR}"

	if [[ -z "${SETTINGSFILES[@]}" ]]
	then
		[ ! -z ${DCONFFILE} ] || $(echo "" >> ${DCONFFILE})
		echo "[${_path}]" >> ${DCONFFILE}
		echo "${_key}=${_value}" >> ${DCONFFILE}
	else
		if grep -q "^(?!#)${_key}" ${SETTINGSFILES[@]}
		then
			sed -i "s/${_key}\s*=\s*.*/${_key}=${_value}/g" ${SETTINGSFILES[@]}
		else
			sed -i "\|\[${_path}]|a\\${_key}=${_value}" ${SETTINGSFILES[@]}
		fi
	fi

	dconf update
}

# Function to configure DConf locks for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_lock 'org/gnome/login-screen' 'banner-message-enable' 'local.d' 'banner'
#
function dconf_lock {
	local _key=$1 _setting=$2 _db=$3 _lockFile=$4

	# Check sanity of the input
	if [ $# -ne "4" ]
	then
		echo "Usage: dconf_lock 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_lockfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	LOCKFILES=$(grep -r "^/${_key}/${_setting}$" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1)
	LOCKSFOLDER="/etc/dconf/db/${_db}/locks"

	mkdir -p "${LOCKSFOLDER}"

	if [[ -z "${LOCKFILES}" ]]
	then
		echo "/${_key}/${_setting}" >> "/etc/dconf/db/${_db}/locks/${_lockFile}"
	fi
}


include_dconf_settings

dconf_settings 'org/gnome/desktop/screensaver' 'lock-delay' "uint32 ${var_screensaver_lock_delay}" 'local.d' '00-security-settings'
dconf_lock 'org/gnome/desktop/screensaver' 'lock-delay' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: "Set GNOME3 Screensaver Lock Delay After Activation Period"
  ini_file:
    dest: "/etc/dconf/db/local.d/00-security-settings"
    section: "org/gnome/desktop/screensaver"
    option: lock-delay
    value: uint32 5
    create: yes
  tags:
    - dconf_gnome_screensaver_lock_delay
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80370-0
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - PCI-DSS-Req-8.1.8
    - DISA-STIG-RHEL-07-010110
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Prevent user modification of GNOME lock-delay"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/desktop/screensaver/lock-delay'
    line: '/org/gnome/desktop/screensaver/lock-delay'
    create: yes
  tags:
    - dconf_gnome_screensaver_lock_delay
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80370-0
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - PCI-DSS-Req-8.1.8
    - DISA-STIG-RHEL-07-010110
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Ensure Users Cannot Change GNOME3 Screensaver Settings   [ref]

If not already configured, ensure that users cannot change GNOME3 screensaver lock settings by adding /org/gnome/desktop/screensaver/lock-delay to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:

/org/gnome/desktop/screensaver/lock-delay
After the settings have been set, run dconf update.

Warning:  When selecting this rule in a profile, make sure that rule with ID dconf_use_text_backend is selected as well: dconf-related rules can't be checked by OVAL if dconf is using a binary database as it's data backend. dconf has to be forced to use config files directly as backend, as those config files are checked by OVAL probes.
Rationale:

A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80371-8

References:  RHEL-07-010081, SV-87807r4_rule, 1, 12, 15, 16, DSS05.04, DSS05.10, DSS06.10, 3.1.10, CCI-000057, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-11(a), PR.AC-7, FMT_MOF_EXT.1, SRG-OS-00029-GPOS-0010

Remediation Shell script:   (show)

function include_dconf_settings {
	:
}

# Function to configure DConf settings for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_settings 'org/gnome/login-screen' 'banner-message-enable' 'true' 'local.d' '10-banner'
#
function dconf_settings {
	local _path=$1 _key=$2 _value=$3 _db=$4 _settingFile=$5

	# Check sanity of the input
	if [ $# -ne "5" ]
	then
		echo "Usage: dconf_settings 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_settingsfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	SETTINGSFILES=($(grep -r "\[${_path}]" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1))
	DCONFFILE="/etc/dconf/db/${_db}/${_settingFile}"
	DBDIR="/etc/dconf/db/${_db}"

	mkdir -p "${DBDIR}"

	if [[ -z "${SETTINGSFILES[@]}" ]]
	then
		[ ! -z ${DCONFFILE} ] || $(echo "" >> ${DCONFFILE})
		echo "[${_path}]" >> ${DCONFFILE}
		echo "${_key}=${_value}" >> ${DCONFFILE}
	else
		if grep -q "^(?!#)${_key}" ${SETTINGSFILES[@]}
		then
			sed -i "s/${_key}\s*=\s*.*/${_key}=${_value}/g" ${SETTINGSFILES[@]}
		else
			sed -i "\|\[${_path}]|a\\${_key}=${_value}" ${SETTINGSFILES[@]}
		fi
	fi

	dconf update
}

# Function to configure DConf locks for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_lock 'org/gnome/login-screen' 'banner-message-enable' 'local.d' 'banner'
#
function dconf_lock {
	local _key=$1 _setting=$2 _db=$3 _lockFile=$4

	# Check sanity of the input
	if [ $# -ne "4" ]
	then
		echo "Usage: dconf_lock 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_lockfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	LOCKFILES=$(grep -r "^/${_key}/${_setting}$" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1)
	LOCKSFOLDER="/etc/dconf/db/${_db}/locks"

	mkdir -p "${LOCKSFOLDER}"

	if [[ -z "${LOCKFILES}" ]]
	then
		echo "/${_key}/${_setting}" >> "/etc/dconf/db/${_db}/locks/${_lockFile}"
	fi
}


include_dconf_settings

dconf_lock 'org/gnome/desktop/screensaver' 'lock-delay' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: "Prevent user modification of GNOME lock-delay"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/desktop/screensaver/lock-delay'
    line: '/org/gnome/desktop/screensaver/lock-delay'
    create: yes
  tags:
    - dconf_gnome_screensaver_user_locks
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80371-8
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - DISA-STIG-RHEL-07-010081
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Enable GNOME3 Screensaver Idle Activation   [ref]

To activate the screensaver in the GNOME3 desktop after a period of inactivity, add or set idle-activation-enabled to true in /etc/dconf/db/local.d/00-security-settings. For example:

[org/gnome/desktop/screensaver]
idle-activation-enabled=true
Once the setting has been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:
/org/gnome/desktop/screensaver/idle-activation-enabled
After the settings have been set, run dconf update.

Warning:  When selecting this rule in a profile, make sure that rule with ID dconf_use_text_backend is selected as well: dconf-related rules can't be checked by OVAL if dconf is using a binary database as it's data backend. dconf has to be forced to use config files directly as backend, as those config files are checked by OVAL probes.
Rationale:

A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the session lock.

Enabling idle activation of the screensaver ensures the screensaver will be activated after the idle delay. Applications requiring continuous, real-time screen display (such as network management products) require the login session does not have administrator rights and the display station is located in a controlled-access area.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80111-8

References:  RHEL-07-010100, SV-86523r4_rule, 1, 12, 15, 16, 5.5.5, DSS05.04, DSS05.10, DSS06.10, 3.1.10, CCI-000057, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-11(a), PR.AC-7, FMT_MOF_EXT.1, Req-8.1.8, SRG-OS-000029-GPOS-00010

Remediation Shell script:   (show)

function include_dconf_settings {
	:
}

# Function to configure DConf settings for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_settings 'org/gnome/login-screen' 'banner-message-enable' 'true' 'local.d' '10-banner'
#
function dconf_settings {
	local _path=$1 _key=$2 _value=$3 _db=$4 _settingFile=$5

	# Check sanity of the input
	if [ $# -ne "5" ]
	then
		echo "Usage: dconf_settings 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_settingsfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	SETTINGSFILES=($(grep -r "\[${_path}]" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1))
	DCONFFILE="/etc/dconf/db/${_db}/${_settingFile}"
	DBDIR="/etc/dconf/db/${_db}"

	mkdir -p "${DBDIR}"

	if [[ -z "${SETTINGSFILES[@]}" ]]
	then
		[ ! -z ${DCONFFILE} ] || $(echo "" >> ${DCONFFILE})
		echo "[${_path}]" >> ${DCONFFILE}
		echo "${_key}=${_value}" >> ${DCONFFILE}
	else
		if grep -q "^(?!#)${_key}" ${SETTINGSFILES[@]}
		then
			sed -i "s/${_key}\s*=\s*.*/${_key}=${_value}/g" ${SETTINGSFILES[@]}
		else
			sed -i "\|\[${_path}]|a\\${_key}=${_value}" ${SETTINGSFILES[@]}
		fi
	fi

	dconf update
}

# Function to configure DConf locks for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_lock 'org/gnome/login-screen' 'banner-message-enable' 'local.d' 'banner'
#
function dconf_lock {
	local _key=$1 _setting=$2 _db=$3 _lockFile=$4

	# Check sanity of the input
	if [ $# -ne "4" ]
	then
		echo "Usage: dconf_lock 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_lockfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	LOCKFILES=$(grep -r "^/${_key}/${_setting}$" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1)
	LOCKSFOLDER="/etc/dconf/db/${_db}/locks"

	mkdir -p "${LOCKSFOLDER}"

	if [[ -z "${LOCKFILES}" ]]
	then
		echo "/${_key}/${_setting}" >> "/etc/dconf/db/${_db}/locks/${_lockFile}"
	fi
}


include_dconf_settings

dconf_settings 'org/gnome/desktop/screensaver' 'idle-activation-enabled' 'true' 'local.d' '00-security-settings'
dconf_lock 'org/gnome/desktop/screensaver' 'idle-activation-enabled' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: "Enable GNOME3 Screensaver Idle Activation"
  ini_file:
    dest: "/etc/dconf/db/local.d/00-security-settings"
    section: "org/gnome/desktop/screensaver"
    option: idle_activation_enabled
    value: "true"
    create: yes
  tags:
    - dconf_gnome_screensaver_idle_activation_enabled
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80111-8
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - PCI-DSS-Req-8.1.8
    - CJIS-5.5.5
    - DISA-STIG-RHEL-07-010100
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Prevent user modification of GNOME idle_activation_enabled"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/desktop/screensaver/idle-activation-enabled'
    line: '/org/gnome/desktop/screensaver/idle-activation-enabled'
    create: yes
  tags:
    - dconf_gnome_screensaver_idle_activation_enabled
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80111-8
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - PCI-DSS-Req-8.1.8
    - CJIS-5.5.5
    - DISA-STIG-RHEL-07-010100
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Set GNOME3 Screensaver Inactivity Timeout   [ref]

The idle time-out value for inactivity in the GNOME3 desktop is configured via the idle-delay setting must be set under an appropriate configuration file(s) in the /etc/dconf/db/local.d directory and locked in /etc/dconf/db/local.d/locks directory to prevent user modification.

For example, to configure the system for a 15 minute delay, add the following to /etc/dconf/db/local.d/00-security-settings:

[org/gnome/desktop/session]
idle-delay=uint32 900
Once the setting has been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:
/org/gnome/desktop/session/idle-delay
After the settings have been set, run dconf update.

Warning:  When selecting this rule in a profile, make sure that rule with ID dconf_use_text_backend is selected as well: dconf-related rules can't be checked by OVAL if dconf is using a binary database as it's data backend. dconf has to be forced to use config files directly as backend, as those config files are checked by OVAL probes.
Rationale:

A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME3 can be configured to identify when a user's session has idled and take action to initiate a session lock.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80110-0

References:  RHEL-07-010070, SV-86517r5_rule, 1, 12, 15, 16, 5.5.5, DSS05.04, DSS05.10, DSS06.10, 3.1.10, CCI-000057, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-11(a), PR.AC-7, FMT_MOF_EXT.1, Req-8.1.8, SRG-OS-000029-GPOS-00010

Remediation Shell script:   (show)


inactivity_timeout_value="900"
function include_dconf_settings {
	:
}

# Function to configure DConf settings for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_settings 'org/gnome/login-screen' 'banner-message-enable' 'true' 'local.d' '10-banner'
#
function dconf_settings {
	local _path=$1 _key=$2 _value=$3 _db=$4 _settingFile=$5

	# Check sanity of the input
	if [ $# -ne "5" ]
	then
		echo "Usage: dconf_settings 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_settingsfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	SETTINGSFILES=($(grep -r "\[${_path}]" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1))
	DCONFFILE="/etc/dconf/db/${_db}/${_settingFile}"
	DBDIR="/etc/dconf/db/${_db}"

	mkdir -p "${DBDIR}"

	if [[ -z "${SETTINGSFILES[@]}" ]]
	then
		[ ! -z ${DCONFFILE} ] || $(echo "" >> ${DCONFFILE})
		echo "[${_path}]" >> ${DCONFFILE}
		echo "${_key}=${_value}" >> ${DCONFFILE}
	else
		if grep -q "^(?!#)${_key}" ${SETTINGSFILES[@]}
		then
			sed -i "s/${_key}\s*=\s*.*/${_key}=${_value}/g" ${SETTINGSFILES[@]}
		else
			sed -i "\|\[${_path}]|a\\${_key}=${_value}" ${SETTINGSFILES[@]}
		fi
	fi

	dconf update
}

# Function to configure DConf locks for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_lock 'org/gnome/login-screen' 'banner-message-enable' 'local.d' 'banner'
#
function dconf_lock {
	local _key=$1 _setting=$2 _db=$3 _lockFile=$4

	# Check sanity of the input
	if [ $# -ne "4" ]
	then
		echo "Usage: dconf_lock 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_lockfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	LOCKFILES=$(grep -r "^/${_key}/${_setting}$" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1)
	LOCKSFOLDER="/etc/dconf/db/${_db}/locks"

	mkdir -p "${LOCKSFOLDER}"

	if [[ -z "${LOCKFILES}" ]]
	then
		echo "/${_key}/${_setting}" >> "/etc/dconf/db/${_db}/locks/${_lockFile}"
	fi
}


include_dconf_settings

dconf_settings 'org/gnome/desktop/session' 'idle-delay' "uint32 ${inactivity_timeout_value}" 'local.d' '00-security-settings'
dconf_lock 'org/gnome/desktop/session' 'idle-delay' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: XCCDF Value inactivity_timeout_value # promote to variable
  set_fact:
    inactivity_timeout_value: !!str 900
  tags:
    - always

- name: "Set GNOME3 Screensaver Inactivity Timeout"
  ini_file:
    dest: "/etc/dconf/db/local.d/00-security-settings"
    section: "org/gnome/desktop/screensaver"
    option: idle-delay
    value: "{{ inactivity_timeout_value }}"
    create: yes
  tags:
    - dconf_gnome_screensaver_idle_delay
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80110-0
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - PCI-DSS-Req-8.1.8
    - CJIS-5.5.5
    - DISA-STIG-RHEL-07-010070
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Prevent user modification of GNOME idle-delay"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/desktop/screensaver/idle-delay'
    line: '/org/gnome/desktop/screensaver/idle-delay'
    create: yes
  tags:
    - dconf_gnome_screensaver_idle_delay
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80110-0
    - NIST-800-53-AC-11(a)
    - NIST-800-171-3.1.10
    - PCI-DSS-Req-8.1.8
    - CJIS-5.5.5
    - DISA-STIG-RHEL-07-010070
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Ensure Users Cannot Change GNOME3 Screensaver Lock After Idle Period   [ref]

If not already configured, ensure that users cannot change GNOME3 screensaver lock settings by adding

/org/gnome/desktop/screensaver/lock-enabled
to /etc/dconf/db/local.d/00-security-settings. For example:
/org/gnome/desktop/screensaver/lock-enabled
After the settings have been set, run dconf update.

Warning:  When selecting this rule in a profile, make sure that rule with ID dconf_use_text_backend is selected as well: dconf-related rules can't be checked by OVAL if dconf is using a binary database as it's data backend. dconf has to be forced to use config files directly as backend, as those config files are checked by OVAL probes.
Rationale:

A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absense.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80563-0

References:  RHEL-07-010062, 1, 12, 15, 16, 5.5.5, DSS05.04, DSS05.10, DSS06.10, 3.1.10, CCI-000056, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-11(b), PR.AC-7, FMT_MOF_EXT.1, Req-8.1.8, SRG-OS-000029-GPOS-00010

Remediation Shell script:   (show)

function include_dconf_settings {
	:
}

# Function to configure DConf settings for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_settings 'org/gnome/login-screen' 'banner-message-enable' 'true' 'local.d' '10-banner'
#
function dconf_settings {
	local _path=$1 _key=$2 _value=$3 _db=$4 _settingFile=$5

	# Check sanity of the input
	if [ $# -ne "5" ]
	then
		echo "Usage: dconf_settings 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_settingsfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	SETTINGSFILES=($(grep -r "\[${_path}]" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1))
	DCONFFILE="/etc/dconf/db/${_db}/${_settingFile}"
	DBDIR="/etc/dconf/db/${_db}"

	mkdir -p "${DBDIR}"

	if [[ -z "${SETTINGSFILES[@]}" ]]
	then
		[ ! -z ${DCONFFILE} ] || $(echo "" >> ${DCONFFILE})
		echo "[${_path}]" >> ${DCONFFILE}
		echo "${_key}=${_value}" >> ${DCONFFILE}
	else
		if grep -q "^(?!#)${_key}" ${SETTINGSFILES[@]}
		then
			sed -i "s/${_key}\s*=\s*.*/${_key}=${_value}/g" ${SETTINGSFILES[@]}
		else
			sed -i "\|\[${_path}]|a\\${_key}=${_value}" ${SETTINGSFILES[@]}
		fi
	fi

	dconf update
}

# Function to configure DConf locks for RHEL and Fedora systems.
#
# Example Call(s):
#
#     dconf_lock 'org/gnome/login-screen' 'banner-message-enable' 'local.d' 'banner'
#
function dconf_lock {
	local _key=$1 _setting=$2 _db=$3 _lockFile=$4

	# Check sanity of the input
	if [ $# -ne "4" ]
	then
		echo "Usage: dconf_lock 'dconf_path' 'dconf_setting' 'dconf_db' 'dconf_lockfile'"
		echo "Aborting."
		exit 1
	fi

	# Check for setting in any of the DConf db directories
	LOCKFILES=$(grep -r "^/${_key}/${_setting}$" "/etc/dconf/db/" | grep -v "distro\|ibus" | cut -d":" -f1)
	LOCKSFOLDER="/etc/dconf/db/${_db}/locks"

	mkdir