Guide to the Secure Configuration of Red Hat Enterprise Linux 7

with profile Health Insurance Portability and Accountability Act (HIPAA)
The HIPAA Security Rule establishes U.S. national standards to protect individuals’ electronic personal health information that is created, received, used, or maintained by a covered entity. The Security Rule requires appropriate administrative, physical and technical safeguards to ensure the confidentiality, integrity, and security of electronic protected health information. This profile configures Red Hat Enterprise Linux 7 to the HIPAA Security Rule identified for securing of electronic protected health information.
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 TitleHealth Insurance Portability and Accountability Act (HIPAA)
Profile IDxccdf_org.ssgproject.content_profile_hipaa

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. Cron and At Daemons
    3. Network Routing
    4. Base Services
    5. NFS and RPC
    6. 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 52 groups and 150 rules
Group   Services   Group contains 14 groups and 37 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 5 groups and 16 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 6 rules

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

Rule   Uninstall rsh Package   [ref]

The rsh package contains the client commands for the rsh services

Rationale:

These legacy clients contain numerous security exposures and have been replaced with the more secure SSH package. Even if the server is removed, it is best to ensure the clients are also removed to prevent users from inadvertently attempting to use these commands and therefore exposing their credentials. Note that removing the rsh package removes the clients for rsh,rcp, and rlogin.

Severity: 
unknown
Identifiers and References

Identifiers:  CCE-27274-0

References:  2.3.2, 3.1.13, 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), A.8.2.3, A.13.1.1, A.13.2.1, A.13.2.3, A.14.1.2, A.14.1.3

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
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure rsh is removed
  package:
    name: rsh
    state: absent
  tags:
    - package_rsh_removed
    - unknown_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27274-0
    - NIST-800-171-3.1.13
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_rsh

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

Complexity:low
Disruption:low
Strategy:disable

package --remove=rsh

Rule   Disable rlogin Service   [ref]

The rlogin service, which is available with the rsh-server package and runs as a service through xinetd or separately as a systemd socket, should be disabled. If using xinetd, set disable to yes in /etc/xinetd.d/rlogin. The rlogin socket can be disabled with the following command:

$ sudo systemctl disable rlogin.socket

Rationale:

The rlogin service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27336-7

References:  2.2.17, 1, 11, 12, 14, 15, 16, 3, 5, 8, 9, APO13.01, 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, 3.1.13, 3.4.7, CCI-001436, 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 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.18.1.4, 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.9.4.2, A.9.4.3, AC-17(8), CM-7, IA-5(1)(c), PR.AC-1, PR.AC-3, PR.AC-6, PR.AC-7, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'rlogin.service'
"$SYSTEMCTL_EXEC" disable 'rlogin.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^rlogin.socket\>' && "$SYSTEMCTL_EXEC" disable 'rlogin.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 'rlogin.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service rlogin
  service:
    name: rlogin
    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_rlogin_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27336-7
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  


- name: Disable socket of service rlogin if applicable
  service:
    name: rlogin.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_rlogin_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27336-7
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  

Rule   Disable rexec Service   [ref]

The rexec service, which is available with the rsh-server package and runs as a service through xinetd or separately as a systemd socket, should be disabled. If using xinetd, set disable to yes in /etc/xinetd.d/rexec. The rexec socket can be disabled with the following command:

$ sudo systemctl disable rexec.socket

Rationale:

The rexec service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27408-4

References:  2.2.17, 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, 3.1.13, 3.4.7, CCI-000068, CCI-001436, 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, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'rexec.service'
"$SYSTEMCTL_EXEC" disable 'rexec.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^rexec.socket\>' && "$SYSTEMCTL_EXEC" disable 'rexec.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 'rexec.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service rexec
  service:
    name: rexec
    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_rexec_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27408-4
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  


- name: Disable socket of service rexec if applicable
  service:
    name: rexec.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_rexec_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27408-4
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  

Rule   Disable rsh Service   [ref]

The rsh service, which is available with the rsh-server package and runs as a service through xinetd or separately as a systemd socket, should be disabled. If using xinetd, set disable to yes in /etc/xinetd.d/rsh. The rsh socket can be disabled with the following command:

$ sudo systemctl disable rsh.socket

Rationale:

The rsh service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27337-5

References:  2.2.17, 1, 11, 12, 14, 15, 16, 3, 5, 8, 9, APO13.01, 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, 3.1.13, 3.4.7, CCI-000068, CCI-001436, 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 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.18.1.4, 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.9.4.2, A.9.4.3, AC-17(8), CM-7, IA-5(1)(c), PR.AC-1, PR.AC-3, PR.AC-6, PR.AC-7, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'rsh.service'
"$SYSTEMCTL_EXEC" disable 'rsh.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^rsh.socket\>' && "$SYSTEMCTL_EXEC" disable 'rsh.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 'rsh.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service rsh
  service:
    name: rsh
    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_rsh_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27337-5
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  


- name: Disable socket of service rsh if applicable
  service:
    name: rsh.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_rsh_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27337-5
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  

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

Rule   Remove Rsh Trust Files   [ref]

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

$ sudo rm /etc/hosts.equiv
$ rm ~/.rhosts

Rationale:

Trust files are convenient, but when used in conjunction with the R-services, they can allow unauthenticated access to a system.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27406-8

References:  6.2.14, 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-001436, 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, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

find /home -maxdepth 2 -type f -name .rhosts -exec rm -f '{}' \;

if [ -f /etc/hosts.equiv ]; then
	/bin/rm -f /etc/hosts.equiv
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- block:
    - name: "Detect shosts.equiv Files on the System"
      find:
          paths: /
          recurse: yes
          patterns: shosts.equiv
      check_mode: no
      register: shosts_equiv_locations

    - name: "Remove Rsh Trust Files"
      file:
          path: "{{ item.path }}"
          state: absent
      with_items: "{{ shosts_equiv_locations.files }}"
      when: shosts_equiv_locations and True
  tags:
    - no_rsh_trust_files
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27406-8
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
Group   Telnet   Group contains 3 rules

[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   Remove telnet Clients   [ref]

The telnet client allows users to start connections to other systems via the telnet protocol.

Rationale:

The telnet protocol is insecure and unencrypted. The use of an unencrypted transmission medium could allow an unauthorized user to steal credentials. The ssh package provides an encrypted session and stronger security and is included in Red Hat Enterprise Linux 7.

Severity: 
low
Identifiers and References

Identifiers:  CCE-27305-2

References:  2.3.4, 3.1.13, 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), A.8.2.3, A.13.1.1, A.13.2.1, A.13.2.3, A.14.1.2, A.14.1.3

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
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure telnet is removed
  package:
    name: telnet
    state: absent
  tags:
    - package_telnet_removed
    - low_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27305-2
    - NIST-800-171-3.1.13
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_telnet

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

Complexity:low
Disruption:low
Strategy:disable

package --remove=telnet

Rule   Disable telnet Service   [ref]

The telnet service configuration file /etc/xinetd.d/telnet is not created automatically. If it was created manually, check the /etc/xinetd.d/telnet file and ensure that disable = no is changed to read disable = yes as follows below:

# description: The telnet server serves telnet sessions; it uses \\
#       unencrypted username/password pairs for authentication.
service telnet
{
        flags           = REUSE
        socket_type     = stream

        wait            = no
        user            = root
        server          = /usr/sbin/in.telnetd
        log_on_failure  += USERID
        disable         = yes
}
If the /etc/xinetd.d/telnet file does not exist, make sure that the activation of the telnet service on system boot is disabled via the following command: The rexec socket can be disabled with the following command:
$ sudo systemctl disable rexec.socket

Rationale:

The telnet protocol uses unencrypted network communication, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. The telnet protocol is also subject to man-in-the-middle attacks.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27401-9

References:  2.2.18, 1, 11, 12, 14, 15, 16, 3, 5, 8, 9, APO13.01, 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, 3.1.13, 3.4.7, 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 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.18.1.4, 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.9.4.2, A.9.4.3, AC-17(8), CM-7, IA-5(1)(c), PR.AC-1, PR.AC-3, PR.AC-6, PR.AC-7, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'telnet.service'
"$SYSTEMCTL_EXEC" disable 'telnet.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^telnet.socket\>' && "$SYSTEMCTL_EXEC" disable 'telnet.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 'telnet.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service telnet
  service:
    name: telnet
    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_telnet_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27401-9
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  


- name: Disable socket of service telnet if applicable
  service:
    name: telnet.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_telnet_disabled
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27401-9
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-53-IA-5(1)(c)
    - NIST-800-171-3.1.13
    - NIST-800-171-3.4.7
  

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 3 rules

[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   Disable ypbind Service   [ref]

The ypbind service, which allows the system to act as a client in a NIS or NIS+ domain, should be disabled. The ypbind service can be disabled with the following command:

$ sudo systemctl disable ypbind.service

Rationale:

Disabling the ypbind service ensures the system is not acting as a client in a NIS or NIS+ domain. This service should be disabled unless in use.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27385-4

References:  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-000305, 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, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'ypbind.service'
"$SYSTEMCTL_EXEC" disable 'ypbind.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^ypbind.socket\>' && "$SYSTEMCTL_EXEC" disable 'ypbind.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 'ypbind.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service ypbind
  service:
    name: ypbind
    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_ypbind_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27385-4
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
  


- name: Disable socket of service ypbind if applicable
  service:
    name: ypbind.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_ypbind_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27385-4
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
  

Rule   Remove NIS Client   [ref]

The Network Information Service (NIS), formerly known as Yellow Pages, is a client-server directory service protocol used to distribute system configuration files. The NIS client (ypbind) was used to bind a system to an NIS server and receive the distributed configuration files.

Rationale:

The NIS service is inherently an insecure system that has been vulnerable to DOS attacks, buffer overflows and has poor authentication for querying NIS maps. NIS generally has been replaced by such protocols as Lightweight Directory Access Protocol (LDAP). It is recommended that the service be removed.

Severity: 
unknown
Identifiers and References

Identifiers:  CCE-27396-1

References:  2.3.1, 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)

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 ypbind
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure ypbind is removed
  package:
    name: ypbind
    state: absent
  tags:
    - package_ypbind_removed
    - unknown_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27396-1
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_ypbind

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

Complexity:low
Disruption:low
Strategy:disable

package --remove=ypbind

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   Xinetd   Group contains 2 rules

[ref]   The xinetd service acts as a dedicated listener for some network services (mostly, obsolete ones) and can be used to provide access controls and perform some logging. It has been largely obsoleted by other features, and it is not installed by default. The older Inetd service is not even available as part of Red Hat Enterprise Linux 7.

Rule   Disable xinetd Service   [ref]

The xinetd service can be disabled with the following command:

$ sudo systemctl disable xinetd.service

Rationale:

The xinetd service provides a dedicated listener service for some programs, which is no longer necessary for commonly-used network services. Disabling it ensures that these uncommon services are not running, and also prevents attacks against xinetd itself.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27443-1

References:  2.1.7, 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, 3.4.7, CCI-000305, 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, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'xinetd.service'
"$SYSTEMCTL_EXEC" disable 'xinetd.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^xinetd.socket\>' && "$SYSTEMCTL_EXEC" disable 'xinetd.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 'xinetd.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service xinetd
  service:
    name: xinetd
    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_xinetd_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27443-1
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-171-3.4.7
  


- name: Disable socket of service xinetd if applicable
  service:
    name: xinetd.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_xinetd_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27443-1
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
    - NIST-800-171-3.4.7
  

Rule   Uninstall xinetd Package   [ref]

The xinetd package can be removed with the following command:

$ sudo yum erase xinetd

Rationale:

Removing the xinetd package decreases the risk of the xinetd service's accidental (or intentional) activation.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27354-0

References:  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-000305, 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, PR.AC-3, PR.IP-1, PR.PT-3, PR.PT-4

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 xinetd
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure xinetd is removed
  package:
    name: xinetd
    state: absent
  tags:
    - package_xinetd_removed
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27354-0
    - NIST-800-53-AC-17(8)
    - NIST-800-53-CM-7
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_xinetd

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

Complexity:low
Disruption:low
Strategy:disable

package --remove=xinetd
Group   Chat/Messaging Services   Group contains 2 rules

[ref]   The talk software makes it possible for users to send and receive messages across systems through a terminal session.

Rule   Uninstall talk Package   [ref]

The talk package contains the client program for the Internet talk protocol, which allows the user to chat with other users on different systems. Talk is a communication program which copies lines from one terminal to the terminal of another user. The talk package can be removed with the following command:

$ sudo yum erase talk

Rationale:

The talk software presents a security risk as it uses unencrypted protocols for communications. Removing the talk package decreases the risk of the accidental (or intentional) activation of talk client program.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27432-4

References:  2.3.3, 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)

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 talk
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure talk is removed
  package:
    name: talk
    state: absent
  tags:
    - package_talk_removed
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27432-4
  
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
include remove_talk

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

Complexity:low
Disruption:low
Strategy:disable

package --remove=talk

Rule   Uninstall talk-server Package   [ref]

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

 $ sudo yum erase talk-server

Rationale:

The talk software presents a security risk as it uses unencrypted protocols for communications. Removing the talk-server package decreases the risk of the accidental (or intentional) activation of talk services.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27210-4

References:  2.2.21, 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)

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 talk-server
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Ensure talk-server is removed
  package:
    name: talk-server
    state: absent
  tags:
    - package_talk-server_removed
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27210-4
  
Remediation Puppet snippet:   (show)

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

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

Complexity:low
Disruption:low
Strategy:disable

package --remove=talk-server
Group   Cron and At Daemons   Group contains 1 rule

[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.

Rule   Enable cron Service   [ref]

The crond service is used to execute commands at preconfigured times. It is required by almost all systems to perform necessary maintenance tasks, such as notifying root of system activity. The crond service can be enabled with the following command:

$ sudo systemctl enable crond.service

Rationale:

Due to its usage for maintenance and security-supporting tasks, enabling the cron daemon is essential.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27323-5

References:  5.1.1, 11, 14, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.05, DSS06.06, 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 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-7, PR.IP-1, PR.PT-3

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

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

Complexity:low
Disruption:low
Strategy:enable
- name: Enable service crond
  service:
    name: crond
    enabled: "yes"
    state: "started"
  tags:
    - service_crond_enabled
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
    - CCE-27323-5
    - NIST-800-53-CM-7
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Group   Network Routing   Group contains 1 group and 1 rule

[ref]   A router is a very desirable target for a potential adversary because they fulfill a variety of infrastructure networking roles such as access to network segments, gateways to other networks, filtering, etc. Therefore, if one is required, the system acting as a router should be dedicated to that purpose alone and be stored in a physically secure location. The system's default routing software is Quagga, and provided in an RPM package of the same name.

Group   Disable Quagga if Possible   Group contains 1 rule

[ref]   If Quagga was installed and activated, but the system does not need to act as a router, then it should be disabled and removed.

Rule   Disable Quagga Service   [ref]

The zebra service can be disabled with the following command:

$ sudo systemctl disable zebra.service

Rationale:

Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If routing daemons are used when not required, system network information may be unnecessarily transmitted across the network.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27191-6

References:  12, 15, 8, APO13.01, DSS05.02, 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), 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, PR.PT-4, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'zebra.service'
"$SYSTEMCTL_EXEC" disable 'zebra.service'
# Disable socket activation if we have a unit file for it
"$SYSTEMCTL_EXEC" list-unit-files | grep -q '^zebra.socket\>' && "$SYSTEMCTL_EXEC" disable 'zebra.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 'zebra.service'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable
- name: Disable service zebra
  service:
    name: zebra
    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_zebra_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27191-6
    - NIST-800-53-SC-32
  


- name: Disable socket of service zebra if applicable
  service:
    name: zebra.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_zebra_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-27191-6
    - NIST-800-53-SC-32
  
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 1 group and 1 rule

[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 Servers   Group contains 1 rule

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

Rule   Use Kerberos Security on All Exports   [ref]

Using Kerberos on all exported mounts prevents a malicious client or user from impersonating a system user. To cryptography authenticate users to the NFS server, add sec=krb5:krb5i:krb5p to each export in /etc/exports.

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-27464-7

References:  1, 12, 14, 15, 16, 18, 3, 5, DSS05.04, DSS05.10, DSS06.10, 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), 4.3.3.6.1, 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

Group   SSH Server   Group contains 1 group and 17 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 17 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   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   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   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")
Group   System Settings   Group contains 36 groups and 113 rules

[ref]   Contains rules that check correct system settings.

Group   Installing and Maintaining Software   Group contains 7 groups and 11 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 1 rule

[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   Encrypt Partitions   [ref]

Red Hat Enterprise Linux 7 natively supports partition encryption through the Linux Unified Key Setup-on-disk-format (LUKS) technology. The easiest way to encrypt a partition is during installation time.

For manual installations, select the Encrypt checkbox during partition creation to encrypt the partition. When this option is selected the system will prompt for a passphrase to use in decrypting the partition. The passphrase will subsequently need to be entered manually every time the system boots.

For automated/unattended installations, it is possible to use Kickstart by adding the --encrypted and --passphrase= options to the definition of each partition to be encrypted. For example, the following line would encrypt the root partition:

part / --fstype=ext4 --size=100 --onpart=hda1 --encrypted --passphrase=PASSPHRASE
Any PASSPHRASE is stored in the Kickstart in plaintext, and the Kickstart must then be protected accordingly. Omitting the --passphrase= option from the partition definition will cause the installer to pause and interactively ask for the passphrase during installation.

By default, the Anaconda installer uses aes-xts-plain64 cipher with a minimum 512 bit key size which should be compatible with FIPS enabled.

Detailed information on encrypting partitions using LUKS or LUKS ciphers can be found on the Red Hat Enterprise Linux 7 Documentation web site:
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Security_Guide/sec-Encryption.html.

Rationale:

The risk of a system's physical compromise, particularly mobile systems such as laptops, places its data at risk of compromise. Encrypting this data mitigates the risk of its loss if the system is lost.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27128-8

References:  13, 14, APO01.06, BAI02.01, BAI06.01, DSS04.07, DSS05.03, DSS05.04, DSS05.07, DSS06.02, DSS06.06, 3.13.16, CCI-001199, CCI-002476, 164.308(a)(1)(ii)(D), 164.308(b)(1), 164.310(d), 164.312(a)(1), 164.312(a)(2)(iii), 164.312(a)(2)(iv), 164.312(b), 164.312(c), 164.314(b)(2)(i), 164.312(d), SR 3.4, SR 4.1, 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, SC-13, SC-28(1), PR.DS-1, PR.DS-5, SRG-OS-000405-GPOS-00184, SRG-OS-000185-GPOS-00079

Group   System and Software Integrity   Group contains 2 groups and 2 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   Software Integrity Checking   Group contains 1 group and 2 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 2 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 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   Updating Software   Group contains 5 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 gpgcheck Enabled for All yum Package Repositories   [ref]

To ensure signature checking is not disabled for any repos, remove any lines from files in /etc/yum.repos.d of the form:

gpgcheck=0

Rationale:

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-26876-3

References:  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(a), 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)

sed -i 's/gpgcheck\s*=.*/gpgcheck=1/g' /etc/yum.repos.d/*
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
#
- name: Find All yum Repositories
  find:
    paths: "/etc/yum.repos.d/"
    patterns: "*.repo"
    contains: ^\[.+]$
  register: yum_find

- name: Ensure gpgcheck Enabled For All yum Package Repositories
  with_items: "{{ yum_find.files }}"
  lineinfile:
    create: yes
    dest: "{{ item.path }}"
    regexp: '^gpgcheck'
    line: 'gpgcheck=1'
  tags:
    - ensure_gpgcheck_never_disabled
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-26876-3
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11(a)
    - 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
  

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 Red Hat GPG Key Installed   [ref]

To ensure the system can cryptographically verify base software packages come from Red Hat (and to connect to the Red Hat Network to receive them), the Red Hat GPG key must properly be installed. To install the Red Hat GPG key, run:

$ sudo subscription-manager register
If the system is not connected to the Internet or an RHN Satellite, then install the Red Hat GPG key from trusted media such as the Red Hat installation CD-ROM or DVD. Assuming the disc is mounted in /media/cdrom, use the following command as the root user to import it into the keyring:
$ sudo rpm --import /media/cdrom/RPM-GPG-KEY

Rationale:

Changes to 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. The Red Hat GPG key is necessary to cryptographically verify packages are from Red Hat.

Severity: 
high
Identifiers and References

Identifiers:  CCE-26957-1

References:  1.2.3, 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(a), 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)

# The two fingerprints below are retrieved from https://access.redhat.com/security/team/key
readonly REDHAT_RELEASE_2_FINGERPRINT="567E347AD0044ADE55BA8A5F199E2F91FD431D51"
readonly REDHAT_AUXILIARY_FINGERPRINT="43A6E49C4A38F4BE9ABF2A5345689C882FA658E0"
# Location of the key we would like to import (once it's integrity verified)
readonly REDHAT_RELEASE_KEY="/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release"

RPM_GPG_DIR_PERMS=$(stat -c %a "$(dirname "$REDHAT_RELEASE_KEY")")

# Verify /etc/pki/rpm-gpg directory permissions are safe
if [ "${RPM_GPG_DIR_PERMS}" -le "755" ]
then
  # If they are safe, try to obtain fingerprints from the key file
  # (to ensure there won't be e.g. CRC error).
  # Backup IFS value
  IFS_BKP=$IFS

  IFS=$'\n' GPG_OUT=($(gpg --with-fingerprint --with-colons "$REDHAT_RELEASE_KEY" | grep "^fpr" | cut -d ":" -f 10))

  GPG_RESULT=$?
  # Reset IFS back to default
  IFS=$IFS_BKP
  # No CRC error, safe to proceed
  if [ "${GPG_RESULT}" -eq "0" ]
  then
    echo "${GPG_OUT[*]}" | grep -vE "${REDHAT_RELEASE_2_FINGERPRINT}|${REDHAT_AUXILIARY_FINGERPRINT}" || {
      # If $REDHAT_RELEASE_KEY file doesn't contain any keys with unknown fingerprint, import it
      rpm --import "${REDHAT_RELEASE_KEY}"
    }
  fi
fi
Remediation Ansible snippet:   (show)

Complexity:medium
Disruption:medium
Strategy:restrict
- name: "Read permission of GPG key directory"
  stat:
    path: /etc/pki/rpm-gpg/
  register: gpg_key_directory_permission
  check_mode: no
  tags:
    - ensure_redhat_gpgkey_installed
    - high_severity
    - restrict_strategy
    - medium_complexity
    - medium_disruption
    - CCE-26957-1
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11(a)
    - 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
  

# It should fail if it doesn't find any fingerprints in file - maybe file was not parsed well.

- name: Read signatures in GPG key
  # According to /usr/share/doc/gnupg2/DETAILS fingerprints are in "fpr" record in field 10
  shell: gpg --with-fingerprint --with-colons "/etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release" | grep "^fpr" | cut -d ":" -f 10
  changed_when: False
  register: gpg_fingerprints
  check_mode: no
  tags:
    - ensure_redhat_gpgkey_installed
    - high_severity
    - restrict_strategy
    - medium_complexity
    - medium_disruption
    - CCE-26957-1
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11(a)
    - 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
  

- name: Set Fact - Valid fingerprints
  set_fact:
     gpg_valid_fingerprints: ("567E347AD0044ADE55BA8A5F199E2F91FD431D51" "43A6E49C4A38F4BE9ABF2A5345689C882FA658E0")
  tags:
    - ensure_redhat_gpgkey_installed
    - high_severity
    - restrict_strategy
    - medium_complexity
    - medium_disruption
    - CCE-26957-1
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11(a)
    - 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
  

- name: Import RedHat GPG key
  rpm_key:
    state: present
    key: /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release
  when:
    (gpg_key_directory_permission.stat.mode <= '0755')
    and (( gpg_fingerprints.stdout_lines | difference(gpg_valid_fingerprints)) | length == 0)
    and (gpg_fingerprints.stdout_lines | length > 0)
    and (ansible_distribution == "RedHat")
    and True
  tags:
    - ensure_redhat_gpgkey_installed
    - high_severity
    - restrict_strategy
    - medium_complexity
    - medium_disruption
    - CCE-26957-1
    - NIST-800-53-CM-5(3)
    - NIST-800-53-CM-11(a)
    - 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

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 1 group and 3 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   GNOME Remote Access Settings   Group contains 2 rules

[ref]   GNOME remote access settings that apply to the graphical interface.

Rule   Require Encryption for Remote Access in GNOME3   [ref]

By default, GNOME requires encryption when using Vino for remote access. To prevent remote access encryption from being disabled, add or set require-encryption to true in /etc/dconf/db/local.d/00-security-settings. For example:

[org/gnome/Vino]
require-encryption=true
Once the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:
/org/gnome/Vino/require-encryption
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:

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

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80121-7

References:  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, 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, 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 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/Vino' 'require-encryption' 'true' 'local.d' '00-security-settings'
dconf_lock 'org/gnome/Vino' 'require-encryption' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: "Require Encryption for Remote Access in GNOME3"
  ini_file:
    dest: /etc/dconf/db/local.d/00-security-settings
    section: org/gnome/Vino
    option: require-encryption
    value: "true"
    create: yes
  tags:
    - dconf_gnome_remote_access_encryption
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80121-7
    - NIST-800-53-CM-2(1)(b)
    - NIST-800-171-3.1.13
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Prevent user modification of GNOME3 Encryption for Remote Access"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/Vino/require-encryption'
    line: '/org/gnome/Vino/require-encryption'
    create: yes
  tags:
    - dconf_gnome_remote_access_encryption
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80121-7
    - NIST-800-53-CM-2(1)(b)
    - NIST-800-171-3.1.13
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Require Credential Prompting for Remote Access in GNOME3   [ref]

By default, GNOME does not require credentials when using Vino for remote access. To configure the system to require remote credentials, add or set authentication-methods to ['vnc'] in /etc/dconf/db/local.d/00-security-settings. For example:

[org/gnome/Vino]
authentication-methods=['vnc']
Once the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:
/org/gnome/Vino/authentication-methods
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:

Username and password prompting is required for remote access. Otherwise, non-authorized and nefarious users can access the system freely.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80120-9

References:  3.1.12, 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)

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/Vino' 'authentication-methods' "['vnc']" 'local.d' '00-security-settings'
dconf_lock 'org/gnome/Vino' 'authentication-methods' 'local.d' '00-security-settings-lock'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: "Require Credential Prompting for Remote Access in GNOME3"
  ini_file:
    dest: /etc/dconf/db/local.d/00-security-settings
    section: org/gnome/Vino
    option: authentication-methods
    value: "['vnc']"
    create: yes
  tags:
    - dconf_gnome_remote_access_credential_prompt
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80120-9
    - NIST-800-171-3.1.12
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Prevent user modification of GNOME3 Credential Prompting for Remote Access"
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: '^/org/gnome/Vino/authentication-methods'
    line: '/org/gnome/Vino/authentication-methods'
    create: yes
  tags:
    - dconf_gnome_remote_access_credential_prompt
    - medium_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
    - CCE-80120-9
    - NIST-800-171-3.1.12
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Force dconf to use the textfiles instead of a binary DB   [ref]

By default, DConf uses a binary database as a data backend. The database is compiled from config files by the

dconf update
command. dconf can be configured to look into those text files directly by inserting the
service-db:keyfile/user
directive at the beginning of the
/etc/dconf/profile/user
file.

Rationale:

Unlike text config files, the binary database is impossible to check by OVAL. Therefore, in order to evaluate dconf configuration, both have to be true at the same time - configuration files have to be compliant, and dconf has to be forced to use them as the primary settings storage.

Severity: 
high
Identifiers and References
Remediation Shell script:   (show)


mkdir -p /etc/dconf/profile

if test -f /etc/dconf/profile/user
then
	sed -i '1s|^|service-db:keyfile/user\n|' /etc/dconf/profile/user
else
	echo 'service-db:keyfile/user' > /etc/dconf/profile/user
fi
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
- name: "Remove the existing \"use textfile backend\" directive from the config - it may not be at the file's very top"
  lineinfile:
    path: '/etc/dconf/profile/user'
    regexp: '^service-db:keyfile/user.*'
    state: 'absent'
  check_mode: no
  tags:
    - dconf_use_text_backend
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

- name: "Insert the \" use textfiles backend\" directive at the top of the config file"
  lineinfile:
    path: '/etc/dconf/profile/user'
    regexp: '^service-db:keyfile/user$'
    line: 'service-db:keyfile/user'
    insertbefore: 'BOF'
    create: yes
  check_mode: no
  tags:
    - dconf_use_text_backend
    - high_severity
    - unknown_strategy
    - low_complexity
    - medium_disruption
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Group   Configure Syslog   Group contains 1 group and 1 rule

[ref]   The syslog service has been the default Unix logging mechanism for many years. It has a number of downsides, including inconsistent log format, lack of authentication for received messages, and lack of authentication, encryption, or reliable transport for messages sent over a network. However, due to its long history, syslog is a de facto standard which is supported by almost all Unix applications.

In Red Hat Enterprise Linux 7, rsyslog has replaced ksyslogd as the syslog daemon of choice, and it includes some additional security features such as reliable, connection-oriented (i.e. TCP) transmission of logs, the option to log to database formats, and the encryption of log data en route to a central logging server. This section discusses how to configure rsyslog for best effect, and how to use tools provided with the system to maintain and monitor logs.

Group   Rsyslog Logs Sent To Remote Host   Group contains 1 rule

[ref]   If system logs are to be useful in detecting malicious activities, it is necessary to send logs to a remote server. An intruder who has compromised the root account on a system may delete the log entries which indicate that the system was attacked before they are seen by an administrator.

However, it is recommended that logs be stored on the local host in addition to being sent to the loghost, especially if rsyslog has been configured to use the UDP protocol to send messages over a network. UDP does not guarantee reliable delivery, and moderately busy sites will lose log messages occasionally, especially in periods of high traffic which may be the result of an attack. In addition, remote rsyslog messages are not authenticated in any way by default, so it is easy for an attacker to introduce spurious messages to the central log server. Also, some problems cause loss of network connectivity, which will prevent the sending of messages to the central server. For all of these reasons, it is better to store log messages both centrally and on each host, so that they can be correlated if necessary.

Rule   Ensure Logs Sent To Remote Host   [ref]

To configure rsyslog to send logs to a remote log server, open /etc/rsyslog.conf and read and understand the last section of the file, which describes the multiple directives necessary to activate remote logging. Along with these other directives, the system can be configured to forward its logs to a particular log server by adding or correcting one of the following lines, substituting loghost.example.com appropriately. The choice of protocol depends on the environment of the system; although TCP and RELP provide more reliable message delivery, they may not be supported in all environments.
To use UDP for log message delivery:

*.* @loghost.example.com

To use TCP for log message delivery:
*.* @@loghost.example.com

To use RELP for log message delivery:
*.* :omrelp:loghost.example.com

There must be a resolvable DNS CNAME or Alias record set to "logcollector" for logs to be sent correctly to the centralized logging utility.

Rationale:

A log server (loghost) receives syslog messages from one or more systems. This data can be used as an additional log source in the event a system is compromised and its local logs are suspect. Forwarding log messages to a remote loghost also provides system administrators with a centralized place to view the status of multiple hosts within the enterprise.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27343-3

References:  RHEL-07-031000, SV-86833r2_rule, 4.2.1.4, 1, 13, 14, 15, 16, 2, 3, 5, 6, APO11.04, APO13.01, BAI03.05, BAI04.04, DSS05.04, DSS05.07, MEA02.01, CCI-000366, CCI-001348, CCI-000136, CCI-001851, 164.308(a)(1)(ii)(D), 164.308(a)(5)(ii)(B), 164.308(a)(5)(ii)(C), 164.308(a)(6)(ii), 164.308(a)(8), 164.310(d)(2)(iii), 164.312(b), 164.314(a)(2)(i)(C), 164.314(a)(2)(iii), 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 7.1, SR 7.2, 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.17.2.1, AU-3(2), AU-4(1), AU-9, PR.DS-4, PR.PT-1, FAU_GEN.1.1.c, SRG-OS-000480-GPOS-00227, SRG-OS-000032-VMM-000130

Remediation Shell script:   (show)


rsyslog_remote_loghost_address="logcollector"
# 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/rsyslog.conf' '^\*\.\*' "@@$rsyslog_remote_loghost_address" 'CCE-27343-3' '%s %s'
Remediation Ansible snippet:   (show)

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

- name: "Set rsyslog remote loghost"
  lineinfile:
    dest: /etc/rsyslog.conf
    regexp: "^\\*\\.\\*"
    line: "*.* @@{{ rsyslog_remote_loghost_address }}"
    create: yes
  tags:
    - rsyslog_remote_loghost
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27343-3
    - NIST-800-53-AU-3(2)
    - NIST-800-53-AU-4(1)
    - NIST-800-53-AU-9
    - DISA-STIG-RHEL-07-031000
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Group   Network Configuration and Firewalls   Group contains 1 group and 1 rule

[ref]   Most systems must be connected to a network of some sort, and this brings with it the substantial risk of network attack. This section discusses the security impact of decisions about networking which must be made when configuring a system.

This section also discusses firewalls, network access controls, and other network security frameworks, which allow system-level rules to be written that can limit an attackers' ability to connect to your system. These rules can specify that network traffic should be allowed or denied from certain IP addresses, hosts, and networks. The rules can also specify which of the system's network services are available to particular hosts or networks.

Group   IPSec Support   Group contains 1 rule

[ref]   Support for Internet Protocol Security (IPsec) is provided in Red Hat Enterprise Linux 7 with Libreswan.

Rule   Verify Any Configured IPSec Tunnel Connections   [ref]

Libreswan provides an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. As such, IPsec can be used to circumvent certain network requirements such as filtering. Verify that if any IPsec connection (conn) configured in /etc/ipsec.conf and /etc/ipsec.d exists is an approved organizational connection.

Rationale:

IP tunneling mechanisms can be used to bypass network filtering.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80171-2

References:  RHEL-07-040820, SV-86941r2_rule, 1, 12, 13, 14, 15, 16, 18, 4, 6, 8, 9, APO01.06, APO13.01, DSS01.05, DSS03.01, DSS05.02, DSS05.04, DSS05.07, DSS06.02, CCI-000336, 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), 4.2.3.4, 4.3.3.4, 4.4.3.3, 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.12.1.1, A.12.1.2, A.13.1.1, A.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, 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-4, DE.AE-1, ID.AM-3, PR.AC-5, PR.DS-5, PR.PT-4, SRG-OS-000480-GPOS-00227

Group   Set Boot Loader Password   Group contains 5 rules

[ref]   During the boot process, the boot loader is responsible for starting the execution of the kernel and passing options to it. The boot loader allows for the selection of different kernels - possibly on different partitions or media. The default Red Hat Enterprise Linux 7 boot loader for x86 systems is called GRUB2. Options it can pass to the kernel include single-user mode, which provides root access without any authentication, and the ability to disable SELinux. To prevent local users from modifying the boot parameters and endangering security, protect the boot loader configuration with a password and ensure its configuration file's permissions are set properly.

Rule   Set Boot Loader Password in grub2   [ref]

The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings.

To do so, select a superuser account name and password and and modify the /etc/grub.d/01_users configuration file with the new account name.

Since plaintext passwords are a security risk, generate a hash for the pasword by running the following command:

$ grub2-setpassword
When prompted, enter the password that was selected.

NOTE: It is recommended not to use common administrator account names like root, admin, or administrator for the grub2 superuser account.

Change the superuser to a different username (The default is 'root').
$ sed -i s/root/bootuser/g /etc/grub.d/01_users


To meet FISMA Moderate, the bootloader superuser account and password MUST differ from the root account and password. Once the superuser account and password have been added, update the grub.cfg file by running:
grub2-mkconfig -o /boot/grub2/grub.cfg
NOTE: Do NOT manually add the superuser account and password to the grub.cfg file as the grub2-mkconfig command overwrites this file.

Warning:  To prevent hard-coded passwords, automatic remediation of this control is not available. Remediation must be automated as a component of machine provisioning, or followed manually as outlined above.
Rationale:

Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode. For more information on how to configure the grub2 superuser account and password, please refer to

Severity: 
high
Identifiers and References

Identifiers:  CCE-27309-4

References:  RHEL-07-010480, SV-86585r5_rule, 1.4.2, 1, 11, 12, 14, 15, 16, 18, 3, 5, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.06, DSS06.10, 3.4.5, CCI-000213, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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, 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, A.18.1.4, A.6.1.2, 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, IA-2, IA-2(1), IA-5(e), AC-3, PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.PT-3, FIA_AFL.1, SRG-OS-000080-GPOS-00048

Rule   Verify /boot/grub2/grub.cfg Permissions   [ref]

File permissions for /boot/grub2/grub.cfg should be set to 600. To properly set the permissions of /boot/grub2/grub.cfg, run the command:

$ sudo chmod 600 /boot/grub2/grub.cfg

Rationale:

Proper permissions ensure that only the root user can modify important boot parameters.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27054-6

References:  1.4.1, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.4.5, CCI-000225, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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(7), PR.AC-4, PR.DS-5

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure

chmod 0600 /boot/grub2/grub.cfg
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists
  
- name: Ensure permission 0600 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    mode: 0600
  when: file_exists.stat.exists and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - file_permissions_grub2_cfg
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-27054-6
    - NIST-800-53-AC-6(7)
    - NIST-800-171-3.4.5

Rule   Verify /boot/grub2/grub.cfg User Ownership   [ref]

The file /boot/grub2/grub.cfg should be owned by the root user to prevent destruction or modification of the file. To properly set the owner of /boot/grub2/grub.cfg, run the command:

$ sudo chown root /boot/grub2/grub.cfg 

Rationale:

Only root should be able to modify important boot parameters.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-26860-7

References:  1.4.1, 12, 13, 14, 15, 16, 18, 3, 5, 5.5.2.2, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.4.5, CCI-000225, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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(7), PR.AC-4, PR.DS-5, Req-7.1

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure

chown 0 /boot/grub2/grub.cfg
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists

- name: Ensure owner 0 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    owner: 0
  when: file_exists.stat.exists and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - file_owner_grub2_cfg
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-26860-7
    - NIST-800-53-AC-6(7)
    - NIST-800-171-3.4.5
    - PCI-DSS-Req-7.1
    - CJIS-5.5.2.2

Rule   Set the UEFI Boot Loader Password   [ref]

The grub2 boot loader should have a superuser account and password protection enabled to protect boot-time settings.

To do so, select a superuser account name and password and and modify the /etc/grub.d/01_users configuration file with the new account name.

Since plaintext passwords are a security risk, generate a hash for the pasword by running the following command:

$ grub2-setpassword
When prompted, enter the password that was selected.

NOTE: It is recommended not to use common administrator account names like root, admin, or administrator for the grub2 superuser account.

Change the superuser to a different username (The default is 'root').
$ sed -i s/root/bootuser/g /etc/grub.d/01_users


To meet FISMA Moderate, the bootloader superuser account and password MUST differ from the root account and password. Once the superuser account and password have been added, update the grub.cfg file by running:
grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg
NOTE: Do NOT manually add the superuser account and password to the grub.cfg file as the grub2-mkconfig command overwrites this file.

Warning:  To prevent hard-coded passwords, automatic remediation of this control is not available. Remediation must be automated as a component of machine provisioning, or followed manually as outlined above.
Rationale:

Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode. For more information on how to configure the grub2 superuser account and password, please refer to

Severity: 
medium
Identifiers and References

Identifiers:  CCE-80354-4

References:  RHEL-07-010490, SV-86587r4_rule, 1.4.2, 11, 12, 14, 15, 16, 18, 3, 5, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.03, DSS06.06, 3.4.5, CCI-000213, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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, 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, 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, PR.AC-4, PR.AC-6, PR.PT-3, FIA_AFL.1, SRG-OS-000080-GPOS-00048

Rule   Verify /boot/grub2/grub.cfg Group Ownership   [ref]

The file /boot/grub2/grub.cfg should be group-owned by the root group to prevent destruction or modification of the file. To properly set the group owner of /boot/grub2/grub.cfg, run the command:

$ sudo chgrp root /boot/grub2/grub.cfg

Rationale:

The root group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-26812-8

References:  1.4.1, 12, 13, 14, 15, 16, 18, 3, 5, 5.5.2.2, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.4.5, CCI-000225, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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(7), PR.AC-4, PR.DS-5, Req-7.1

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:configure

chgrp 0 /boot/grub2/grub.cfg
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:configure
- name: Test for existence /boot/grub2/grub.cfg
  stat:
    path: /boot/grub2/grub.cfg
  register: file_exists

- name: Ensure group owner 0 on /boot/grub2/grub.cfg
  file:
    path: /boot/grub2/grub.cfg
    group: 0
  when: file_exists.stat.exists and (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
  tags:
    - file_groupowner_grub2_cfg
    - medium_severity
    - configure_strategy
    - low_complexity
    - low_disruption
    - CCE-26812-8
    - NIST-800-53-AC-6(7)
    - NIST-800-171-3.4.5
    - PCI-DSS-Req-7.1
    - CJIS-5.5.2.2
Group   SELinux   Group contains 1 group and 7 rules

[ref]   SELinux is a feature of the Linux kernel which can be used to guard against misconfigured or compromised programs. SELinux enforces the idea that programs should be limited in what files they can access and what actions they can take.

The default SELinux policy, as configured on Red Hat Enterprise Linux 7, has been sufficiently developed and debugged that it should be usable on almost any system with minimal configuration and a small amount of system administrator training. This policy prevents system services - including most of the common network-visible services such as mail servers, FTP servers, and DNS servers - from accessing files which those services have no valid reason to access. This action alone prevents a huge amount of possible damage from network attacks against services, from trojaned software, and so forth.

This guide recommends that SELinux be enabled using the default (targeted) policy on every Red Hat Enterprise Linux 7 system, unless that system has unusual requirements which make a stronger policy appropriate.

For more information on SELinux, see https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/SELinux_Users_and_Administrators_Guide.

Group   SELinux - Booleans   Group contains 3 rules

[ref]   Enable or Disable runtime customization of SELinux system policies without having to reload or recompile the SELinux policy.

Rule   disable the selinuxuser_execstack SELinux Boolean   [ref]

By default, the SELinux boolean selinuxuser_execstack is enabled. This setting should be disabled as unconfined executables should not be able to make their stack executable. To disable the selinuxuser_execstack SELinux boolean, run the following command:

$ sudo setsebool -P selinuxuser_execstack off

Rationale:

Severity: 
medium
Identifiers and References

References:  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)

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

var_selinuxuser_execstack="false"

setsebool -P selinuxuser_execstack $var_selinuxuser_execstack
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: XCCDF Value var_selinuxuser_execstack # promote to variable
  set_fact:
    var_selinuxuser_execstack: !!str false
  tags:
    - always

- name: Ensure libsemanage-python installed
  package:
    name: libsemanage-python
    state: latest
  tags:
    - skip_ansible_lint # [ANSIBLE0010] Skipping lint because ANSIBLE0010 is a bad security practice

- name: Set SELinux boolean selinuxuser_execstack accordingly
  seboolean:
    name: selinuxuser_execstack
    state: "{{ var_selinuxuser_execstack }}"
    persistent: yes
  tags:
    - sebool_selinuxuser_execstack
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
  

Rule   Enable the selinuxuser_execmod SELinux Boolean   [ref]

By default, the SELinux boolean selinuxuser_execmod is enabled. If this setting is disabled, it should be enabled. To enable the selinuxuser_execmod SELinux boolean, run the following command:

$ sudo setsebool -P selinuxuser_execmod on

Rationale:

Severity: 
medium
Identifiers and References

References:  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)

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

var_selinuxuser_execmod="true"

setsebool -P selinuxuser_execmod $var_selinuxuser_execmod
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: XCCDF Value var_selinuxuser_execmod # promote to variable
  set_fact:
    var_selinuxuser_execmod: !!str true
  tags:
    - always

- name: Ensure libsemanage-python installed
  package:
    name: libsemanage-python
    state: latest
  tags:
    - skip_ansible_lint # [ANSIBLE0010] Skipping lint because ANSIBLE0010 is a bad security practice

- name: Set SELinux boolean selinuxuser_execmod accordingly
  seboolean:
    name: selinuxuser_execmod
    state: "{{ var_selinuxuser_execmod }}"
    persistent: yes
  tags:
    - sebool_selinuxuser_execmod
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
  

Rule   Disable the selinuxuser_execheap SELinux Boolean   [ref]

By default, the SELinux boolean selinuxuser_execheap is disabled. If this setting is enabled, it should be disabled. To disable the selinuxuser_execheap SELinux boolean, run the following command:

$ sudo setsebool -P selinuxuser_execheap off

Rationale:

Severity: 
medium
Identifiers and References

References:  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)

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:enable

var_selinuxuser_execheap="false"

setsebool -P selinuxuser_execheap $var_selinuxuser_execheap
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: XCCDF Value var_selinuxuser_execheap # promote to variable
  set_fact:
    var_selinuxuser_execheap: !!str false
  tags:
    - always

- name: Ensure libsemanage-python installed
  package:
    name: libsemanage-python
    state: latest
  tags:
    - skip_ansible_lint # [ANSIBLE0010] Skipping lint because ANSIBLE0010 is a bad security practice

- name: Set SELinux boolean selinuxuser_execheap accordingly
  seboolean:
    name: selinuxuser_execheap
    state: "{{ var_selinuxuser_execheap }}"
    persistent: yes
  tags:
    - sebool_selinuxuser_execheap
    - medium_severity
    - enable_strategy
    - low_complexity
    - low_disruption
  

Rule   Ensure SELinux Not Disabled in /etc/default/grub   [ref]

SELinux can be disabled at boot time by an argument in /etc/default/grub. Remove any instances of selinux=0 from the kernel arguments in that file to prevent SELinux from being disabled at boot.

Rationale:

Disabling a major host protection feature, such as SELinux, at boot time prevents it from confining system services at boot time. Further, it increases the chances that it will remain off during system operation.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-26961-3

References:  1.6.1.1, 1, 11, 12, 13, 14, 15, 16, 18, 3, 4, 5, 6, 8, 9, APO01.06, APO11.04, APO13.01, BAI03.05, DSS01.05, DSS03.01, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.03, DSS06.06, MEA02.01, 3.1.2, 3.7.2, CCI-000022, CCI-000032, 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), 4.2.3.4, 4.3.3.2.2, 4.3.3.3.9, 4.3.3.4, 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, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, 4.4.3.3, 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 2.10, 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.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, 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.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, 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.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-3, AC-3(3), AC-3(4), AC-4, AC-6, AU-9, SI-6(a), DE.AE-1, ID.AM-3, PR.AC-4, PR.AC-5, PR.AC-6, PR.DS-5, PR.PT-1, PR.PT-3, PR.PT-4

Remediation Shell script:   (show)


sed -i --follow-symlinks "s/selinux=0//gI" /etc/default/grub /etc/grub2.cfg /etc/grub.d/*
sed -i --follow-symlinks "s/enforcing=0//gI" /etc/default/grub /etc/grub2.cfg /etc/grub.d/*
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Ensure SELinux Not Disabled in /etc/default/grub
  replace:
    dest: /etc/default/grub
    regexp: selinux=0
  tags:
    - grub2_enable_selinux
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-26961-3
    - NIST-800-53-AC-3
    - NIST-800-53-AC-3(3)
    - NIST-800-53-AC-3(4)
    - NIST-800-53-AC-4
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9
    - NIST-800-53-SI-6(a)
    - NIST-800-171-3.1.2
    - NIST-800-171-3.7.2
  

Rule   Configure SELinux Policy   [ref]

The SELinux targeted policy is appropriate for general-purpose desktops and servers, as well as systems in many other roles. To configure the system to use this policy, add or correct the following line in /etc/selinux/config:

SELINUXTYPE=targeted
Other policies, such as mls, provide additional security labeling and greater confinement but are not compatible with many general-purpose use cases.

Rationale:

Setting the SELinux policy to targeted or a more specialized policy ensures the system will confine processes that are likely to be targeted for exploitation, such as network or system services.

Note: During the development or debugging of SELinux modules, it is common to temporarily place non-production systems in permissive mode. In such temporary cases, SELinux policies should be developed, and once work is completed, the system should be reconfigured to targeted.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27279-9

References:  RHEL-07-020220, SV-86615r4_rule, 1.6.1.3, 1, 11, 12, 13, 14, 15, 16, 18, 3, 4, 5, 6, 8, 9, APO01.06, APO11.04, APO13.01, BAI03.05, DSS01.05, DSS03.01, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.03, DSS06.06, MEA02.01, 3.1.2, 3.7.2, CCI-002696, 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), 4.2.3.4, 4.3.3.2.2, 4.3.3.3.9, 4.3.3.4, 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, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, 4.4.3.3, 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 2.10, 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.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, 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.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, 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.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-3, AC-3(3), AC-3(4), AC-4, AC-6, AU-9, SI-6(a), DE.AE-1, ID.AM-3, PR.AC-4, PR.AC-5, PR.AC-6, PR.DS-5, PR.PT-1, PR.PT-3, PR.PT-4, SRG-OS-000445-GPOS-00199

Remediation Shell script:   (show)


var_selinux_policy_name="targeted"
# 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/sysconfig/selinux' '^SELINUXTYPE=' $var_selinux_policy_name 'CCE-27279-9' '%s=%s'
Remediation Ansible snippet:   (show)

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

- name: "Configure SELinux Policy"
  lineinfile:
    path: /etc/sysconfig/selinux
    regexp: '^SELINUXTYPE='
    line: "SELINUXTYPE={{ var_selinux_policy_name }}"
    create: yes
  tags:
    - selinux_policytype
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27279-9
    - NIST-800-53-AC-3
    - NIST-800-53-AC-3(3)
    - NIST-800-53-AC-3(4)
    - NIST-800-53-AC-4
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9
    - NIST-800-53-SI-6(a)
    - NIST-800-171-3.1.2
    - NIST-800-171-3.7.2
    - DISA-STIG-RHEL-07-020220
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")

Rule   Ensure No Daemons are Unconfined by SELinux   [ref]

Daemons for which the SELinux policy does not contain rules will inherit the context of the parent process. Because daemons are launched during startup and descend from the init process, they inherit the initrc_t context.

To check for unconfined daemons, run the following command:

$ sudo ps -eZ | egrep "initrc" | egrep -vw "tr|ps|egrep|bash|awk" | tr ':' ' ' | awk '{ print $NF }'
It should produce no output in a well-configured system.

Warning:  Automatic remediation of this control is not available. Remediation can be achieved by amending SELinux policy or stopping the unconfined daemons as outlined above.
Rationale:

Daemons which run with the initrc_t context may cause AVC denials, or allow privileges that the daemon does not require.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27288-0

References:  1.6.1.6, 1, 11, 12, 13, 14, 15, 16, 18, 3, 5, 6, 9, APO01.06, APO11.04, BAI03.05, BAI10.01, BAI10.02, BAI10.03, BAI10.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.06, MEA02.01, 3.1.2, 3.1.5, 3.7.2, 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), 4.3.3.3.9, 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 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, CM-7, SC-39, PR.AC-4, PR.DS-5, PR.IP-1, PR.PT-1, PR.PT-3

Rule   Ensure SELinux State is Enforcing   [ref]

The SELinux state should be set to enforcing at system boot time. In the file /etc/selinux/config, add or correct the following line to configure the system to boot into enforcing mode:

SELINUX=enforcing

Rationale:

Setting the SELinux state to enforcing ensures SELinux is able to confine potentially compromised processes to the security policy, which is designed to prevent them from causing damage to the system or further elevating their privileges.

Severity: 
high
Identifiers and References

Identifiers:  CCE-27334-2

References:  RHEL-07-020210, SV-86613r3_rule, 1.6.1.2, 1, 11, 12, 13, 14, 15, 16, 18, 3, 4, 5, 6, 8, 9, APO01.06, APO11.04, APO13.01, BAI03.05, DSS01.05, DSS03.01, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.02, DSS06.03, DSS06.06, MEA02.01, 3.1.2, 3.7.2, CCI-002165, CCI-002696, 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), 4.2.3.4, 4.3.3.2.2, 4.3.3.3.9, 4.3.3.4, 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, 4.3.4.4.7, 4.4.2.1, 4.4.2.2, 4.4.2.4, 4.4.3.3, 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 2.10, 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.10.1.1, A.11.1.4, A.11.1.5, A.11.2.1, A.12.1.1, A.12.1.2, 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.13.1.2, A.13.1.3, A.13.2.1, A.13.2.2, 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.9.2.1, A.9.2.3, A.9.4.1, A.9.4.4, A.9.4.5, AC-3, AC-3(3), AC-3(4), AC-4, AC-6, AU-9, SI-6(a), DE.AE-1, ID.AM-3, PR.AC-4, PR.AC-5, PR.AC-6, PR.DS-5, PR.PT-1, PR.PT-3, PR.PT-4, SRG-OS-000445-GPOS-00199

Remediation Shell script:   (show)


var_selinux_state="enforcing"
# 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/sysconfig/selinux' '^SELINUX=' $var_selinux_state 'CCE-27334-2' '%s=%s'

fixfiles onboot
fixfiles -f relabel
Remediation Ansible snippet:   (show)

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

- name: "Ensure SELinux State is Enforcing"
  lineinfile:
    path: /etc/sysconfig/selinux
    regexp: '^SELINUX='
    line: "SELINUX={{ var_selinux_state }}"
    create: yes
  tags:
    - selinux_state
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - CCE-27334-2
    - NIST-800-53-AC-3
    - NIST-800-53-AC-3(3)
    - NIST-800-53-AC-3(4)
    - NIST-800-53-AC-4
    - NIST-800-53-AC-6
    - NIST-800-53-AU-9
    - NIST-800-53-SI-6(a)
    - NIST-800-171-3.1.2
    - NIST-800-171-3.7.2
    - DISA-STIG-RHEL-07-020210
  when:  # Bare-metal/VM task, not applicable for containers
    - (ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker")
Group   Account and Access Control   Group contains 4 groups and 9 rules

[ref]   In traditional Unix security, if an attacker gains shell access to a certain login account, they can perform any action or access any file to which that account has access. Therefore, making it more difficult for unauthorized people to gain shell access to accounts, particularly to privileged accounts, is a necessary part of securing a system. This section introduces mechanisms for restricting access to accounts under Red Hat Enterprise Linux 7.

Group   Protect Physical Console Access   Group contains 5 rules

[ref]   It is impossible to fully protect a system from an attacker with physical access, so securing the space in which the system is located should be considered a necessary step. However, there are some steps which, if taken, make it more difficult for an attacker to quickly or undetectably modify a system from its console.

Rule   Require Authentication for Single User Mode   [ref]

Single-user mode is intended as a system recovery method, providing a single user root access to the system by providing a boot option at startup. By default, no authentication is performed if single-user mode is selected.

By default, single-user mode is protected by requiring a password and is set in /usr/lib/systemd/system/rescue.service.

Rationale:

This prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27287-2

References:  RHEL-07-010481, SV-92519r2_rule, 1.4.3, 1, 11, 12, 14, 15, 16, 18, 3, 5, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.03, DSS06.06, DSS06.10, 3.1.1, 3.4.5, CCI-000213, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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, 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, A.18.1.4, A.6.1.2, 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, IA-2, IA-2(1), AC-3, PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.PT-3, FIA_AFL.1, SRG-OS-000080-GPOS-00048, RHEL-07-010481, SV-92519r2_rule

Remediation Shell script:   (show)


service_file="/usr/lib/systemd/system/rescue.service"

sulogin="/sbin/sulogin"

if grep "^ExecStart=.*" "$service_file" ; then
    sed -i "s%^ExecStart=.*%ExecStart=-$sulogin rescue%" "$service_file"
else
    echo "ExecStart=-$sulogin rescue" >> "$service_file"
fi

Rule   Disable Ctrl-Alt-Del Burst Action   [ref]

By default, SystemD will reboot the system if the Ctrl-Alt-Del key sequence is pressed Ctrl-Alt-Delete more than 7 times in 2 seconds.

To configure the system to ignore the CtrlAltDelBurstAction setting, add or modify the following to /etc/systemd/system.conf:

CtrlAltDelBurstAction=none

Warning:  Disabling the Ctrl-Alt-Del key sequence in /etc/init/control-alt-delete.conf DOES NOT disable the Ctrl-Alt-Del key sequence if running in runlevel 6 (e.g. in GNOME, KDE, etc.)! The Ctrl-Alt-Del key sequence will only be disabled if running in the non-graphical runlevel 3.
Rationale:

A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.

Severity: 
high
Identifiers and References

Identifiers:  CCE-80449-2

References:  12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.07, DSS06.02, 3.4.5, CCI-000366, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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 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/systemd/system.conf' '^CtrlAltDelBurstAction=' 'none' 'CCE-80449-2' '%s=%s'
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:disable

- name: Disable Ctrl-Alt-Del Burst Action
  lineinfile:
    dest: /etc/systemd/system.conf
    state: present
    regexp: ^CtrlAltDelBurstAction
    line: "CtrlAltDelBurstAction=none"
  tags:
    - disable_ctrlaltdel_burstaction
    - high_severity
    - disable_strategy
    - low_complexity
    - low_disruption
    - CCE-80449-2
    - NIST-800-53-AC-6
    - NIST-800-171-3.4.5
  

Rule   Verify that Interactive Boot is Disabled   [ref]

Red Hat Enterprise Linux 7 systems support an "interactive boot" option that can be used to prevent services from being started. On a Red Hat Enterprise Linux 7 system, interactive boot can be enabled by providing a 1, yes, true, or on value to the systemd.confirm_spawn kernel argument in /etc/default/grub. Remove any instance of

systemd.confirm_spawn=(1|yes|true|on)
from the kernel arguments in that file to disable interactive boot. It is also required to change the runtime configuration, run:
/sbin/grubby --update-kernel=ALL --remove-args="systemd.confirm_spawn"

Rationale:

Using interactive boot, the console user could disable auditing, firewalls, or other services, weakening system security.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-27335-9

References:  11, 12, 14, 15, 16, 18, 3, 5, DSS05.02, DSS05.04, DSS05.05, DSS05.07, DSS06.03, DSS06.06, 3.1.2, 3.4.5, CCI-000213, 164.308(a)(1)(ii)(B), 164.308(a)(7)(i), 164.308(a)(7)(ii)(A), 164.310(a)(1), 164.310(a)(2)(i), 164.310(a)(2)(ii), 164.310(a)(2)(iii), 164.310(b), 164.310(c), 164.310(d)(1), 164.310(d)(2)(iii), 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, 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, 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, SC-2</