Guide to the Secure Configuration of Red Hat OpenShift Container Platform 4

with profile Australian Cyber Security Centre (ACSC) Essential Eight
This profile contains configuration checks for Red Hat Enterprise Linux CoreOS that align to the Australian Cyber Security Centre (ACSC) Essential Eight. A copy of the Essential Eight in Linux Environments guide can be found at the ACSC website: https://www.cyber.gov.au/publications/essential-eight-in-linux-environments
This guide presents a catalog of security-relevant configuration settings for Red Hat OpenShift Container Platform 4. 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 NIST National Checklist Program (NCP), which provides required settings for the United States Government, 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 TitleAustralian Cyber Security Centre (ACSC) Essential Eight
Profile IDxccdf_org.ssgproject.content_profile_e8

CPE Platforms

  • cpe:/a:redhat:openshift_container_platform:4.1

Revision History

Current version: 0.1.50

  • draft (as of 2020-05-15)

Table of Contents

  1. System Settings
    1. Account and Access Control
    2. System Accounting with auditd
    3. SELinux
    4. File Permissions and Masks
    5. Installing and Maintaining Software
  2. Services
    1. SSH Server

Checklist

Group   Guide to the Secure Configuration of Red Hat OpenShift Container Platform 4   Group contains 23 groups and 51 rules
Group   System Settings   Group contains 19 groups and 41 rules

[ref]   Contains rules that check correct system settings.

Group   Account and Access Control   Group contains 3 groups and 2 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 OpenShift Container Platform 4.

Group   Protect Accounts by Restricting Password-Based Login   Group contains 2 groups and 2 rules

[ref]   Conventionally, Unix shell accounts are accessed by providing a username and password to a login program, which tests these values for correctness using the /etc/passwd and /etc/shadow files. Password-based login is vulnerable to guessing of weak passwords, and to sniffing and man-in-the-middle attacks against passwords entered over a network or at an insecure console. Therefore, mechanisms for accessing accounts by entering usernames and passwords should be restricted to those which are operationally necessary.

Group   Verify Proper Storage and Existence of Password Hashes   Group contains 1 rule

[ref]   By default, password hashes for local accounts are stored in the second field (colon-separated) in /etc/shadow. This file should be readable only by processes running with root credentials, preventing users from casually accessing others' password hashes and attempting to crack them. However, it remains possible to misconfigure the system and store password hashes in world-readable files such as /etc/passwd, or to even store passwords themselves in plaintext on the system. Using system-provided tools for password change/creation should allow administrators to avoid such misconfiguration.

Rule   Prevent Login to Accounts With Empty Password   [ref]

If an account is configured for password authentication but does not have an assigned password, it may be possible to log into the account without authentication. Remove any instances of the nullok option in /etc/pam.d/system-auth to prevent logins with empty passwords.

Rationale:

If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.

Severity: 
high
Identifiers and References

Identifiers:  CCE-82553-9

References:  1, 12, 13, 14, 15, 16, 18, 3, 5, 5.5.2, APO01.06, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.02, DSS06.03, DSS06.10, 3.1.1, 3.1.5, 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), 4.3.3.2.2, 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, 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 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.18.1.4, 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.9.2.2, 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-5(1)(a), IA-5(c), CM-6(a), PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.DS-5, FIA_AFL.1, Req-8.2.3, SRG-OS-000480-GPOS-00227

Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%20Generated%20by%20authselect%20on%20Sat%20Oct%2027%2014%3A59%3A36%202018%0A%23%20Do%20not%20modify%20this%20file%20manually.%0A%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_env.so%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_faildelay.so%20delay%3D2000000%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_fprintd.so%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20try_first_pass%0Aauth%20%20%20%20%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet_success%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20forward_pass%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3C%201000%20quiet%0Aaccount%20%20%20%20%20%5Bdefault%3Dbad%20success%3Dok%20user_unknown%3Dignore%5D%20pam_sss.so%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_permit.so%0A%0Apassword%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_pwquality.so%20try_first_pass%20local_users_only%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20sha512%20shadow%20try_first_pass%20use_authtok%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20use_authtok%0Apassword%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_keyinit.so%20revoke%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_limits.so%0A-session%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_systemd.so%0Asession%20%20%20%20%20%5Bsuccess%3D1%20default%3Dignore%5D%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20service%20in%20crond%20quiet%20use_uid%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%0A
        filesystem: root
        mode: 0644
        path: /etc/pam.d/password-auth
      - contents:
          source: data:,%23%20Generated%20by%20authselect%20on%20Sat%20Oct%2027%2014%3A59%3A36%202018%0A%23%20Do%20not%20modify%20this%20file%20manually.%0A%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_env.so%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_faildelay.so%20delay%3D2000000%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_fprintd.so%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet%0Aauth%20%20%20%20%20%20%20%20%5Bdefault%3D1%20ignore%3Dignore%20success%3Dok%5D%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20try_first_pass%0Aauth%20%20%20%20%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3E%3D%201000%20quiet_success%0Aauth%20%20%20%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20forward_pass%0Aauth%20%20%20%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_localuser.so%0Aaccount%20%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20uid%20%3C%201000%20quiet%0Aaccount%20%20%20%20%20%5Bdefault%3Dbad%20success%3Dok%20user_unknown%3Dignore%5D%20pam_sss.so%0Aaccount%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_permit.so%0A%0Apassword%20%20%20%20requisite%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_pwquality.so%20try_first_pass%20local_users_only%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%20sha512%20shadow%20try_first_pass%20use_authtok%0Apassword%20%20%20%20sufficient%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%20use_authtok%0Apassword%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_deny.so%0A%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_keyinit.so%20revoke%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_limits.so%0A-session%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_systemd.so%0Asession%20%20%20%20%20%5Bsuccess%3D1%20default%3Dignore%5D%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_succeed_if.so%20service%20in%20crond%20quiet%20use_uid%0Asession%20%20%20%20%20required%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_unix.so%0Asession%20%20%20%20%20optional%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20pam_sss.so%0A
        filesystem: root
        mode: 0644
        path: /etc/pam.d/system-auth
Group   Restrict Root Logins   Group contains 1 rule

[ref]   Direct root logins should be allowed only for emergency use. In normal situations, the administrator should access the system via a unique unprivileged account, and then use su or sudo to execute privileged commands. Discouraging administrators from accessing the root account directly ensures an audit trail in organizations with multiple administrators. Locking down the channels through which root can connect directly also reduces opportunities for password-guessing against the root account. The login program uses the file /etc/securetty to determine which interfaces should allow root logins. The virtual devices /dev/console and /dev/tty* represent the system consoles (accessible via the Ctrl-Alt-F1 through Ctrl-Alt-F6 keyboard sequences on a default installation). The default securetty file also contains /dev/vc/*. These are likely to be deprecated in most environments, but may be retained for compatibility. Root should also be prohibited from connecting via network protocols. Other sections of this document include guidance describing how to prevent root from logging in via SSH.

Rule   Verify Only Root Has UID 0   [ref]

If any account other than root has a UID of 0, this misconfiguration should be investigated and the accounts other than root should be removed or have their UID changed.
If the account is associated with system commands or applications the UID should be changed to one greater than "0" but less than "1000." Otherwise assign a UID greater than "1000" that has not already been assigned.

Rationale:

An account has root authority if it has a UID of 0. Multiple accounts with a UID of 0 afford more opportunity for potential intruders to guess a password for a privileged account. Proper configuration of sudo is recommended to afford multiple system administrators access to root privileges in an accountable manner.

Severity: 
high
Identifiers and References

Identifiers:  CCE-82699-0

References:  6.2.5, 1, 12, 13, 14, 15, 16, 18, 3, 5, APO01.06, DSS05.04, DSS05.05, DSS05.07, DSS05.10, DSS06.02, DSS06.03, DSS06.10, 3.1.1, 3.1.5, CCI-000366, 4.3.3.2.2, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, SR 1.1, SR 1.10, SR 1.2, SR 1.3, SR 1.4, SR 1.5, SR 1.7, SR 1.8, SR 1.9, SR 2.1, 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.18.1.4, 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.9.2.2, 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, AC-6(5), IA-4(b), PR.AC-1, PR.AC-4, PR.AC-6, PR.AC-7, PR.DS-5, SRG-OS-000480-GPOS-00227

Group   System Accounting with auditd   Group contains 7 groups and 28 rules

[ref]   The audit service provides substantial capabilities for recording system activities. By default, the service audits about SELinux AVC denials and certain types of security-relevant events such as system logins, account modifications, and authentication events performed by programs such as sudo. Under its default configuration, auditd has modest disk space requirements, and should not noticeably impact system performance.

NOTE: The Linux Audit daemon auditd can be configured to use the augenrules program to read audit rules files (*.rules) located in /etc/audit/rules.d location and compile them to create the resulting form of the /etc/audit/audit.rules configuration file during the daemon startup (default configuration). Alternatively, the auditd daemon can use the auditctl utility to read audit rules from the /etc/audit/audit.rules configuration file during daemon startup, and load them into the kernel. The expected behavior is configured via the appropriate ExecStartPost directive setting in the /usr/lib/systemd/system/auditd.service configuration file. To instruct the auditd daemon to use the augenrules program to read audit rules (default configuration), use the following setting:

ExecStartPost=-/sbin/augenrules --load
in the /usr/lib/systemd/system/auditd.service configuration file. In order to instruct the auditd daemon to use the auditctl utility to read audit rules, use the following setting:
ExecStartPost=-/sbin/auditctl -R /etc/audit/audit.rules
in the /usr/lib/systemd/system/auditd.service configuration file. Refer to [Service] section of the /usr/lib/systemd/system/auditd.service configuration file for further details.

Government networks often have substantial auditing requirements and auditd can be configured to meet these requirements. Examining some example audit records demonstrates how the Linux audit system satisfies common requirements. The following example from Fedora Documentation available at https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/SELinux_Users_and_Administrators_Guide/sect-Security-Enhanced_Linux-Troubleshooting-Fixing_Problems.html#sect-Security-Enhanced_Linux-Fixing_Problems-Raw_Audit_Messages shows the substantial amount of information captured in a two typical "raw" audit messages, followed by a breakdown of the most important fields. In this example the message is SELinux-related and reports an AVC denial (and the associated system call) that occurred when the Apache HTTP Server attempted to access the /var/www/html/file1 file (labeled with the samba_share_t type):
type=AVC msg=audit(1226874073.147:96): avc:  denied  { getattr } for pid=2465 comm="httpd"
path="/var/www/html/file1" dev=dm-0 ino=284133 scontext=unconfined_u:system_r:httpd_t:s0
tcontext=unconfined_u:object_r:samba_share_t:s0 tclass=file

type=SYSCALL msg=audit(1226874073.147:96): arch=40000003 syscall=196 success=no exit=-13
a0=b98df198 a1=bfec85dc a2=54dff4 a3=2008171 items=0 ppid=2463 pid=2465 auid=502 uid=48
gid=48 euid=48 suid=48 fsuid=48 egid=48 sgid=48 fsgid=48 tty=(none) ses=6 comm="httpd"
exe="/usr/sbin/httpd" subj=unconfined_u:system_r:httpd_t:s0 key=(null)
  • msg=audit(1226874073.147:96)
    • The number in parentheses is the unformatted time stamp (Epoch time) for the event, which can be converted to standard time by using the date command.
  • { getattr }
    • The item in braces indicates the permission that was denied. getattr indicates the source process was trying to read the target file's status information. This occurs before reading files. This action is denied due to the file being accessed having the wrong label. Commonly seen permissions include getattr, read, and write.
  • comm="httpd"
    • The executable that launched the process. The full path of the executable is found in the exe= section of the system call (SYSCALL) message, which in this case, is exe="/usr/sbin/httpd".
  • path="/var/www/html/file1"
    • The path to the object (target) the process attempted to access.
  • scontext="unconfined_u:system_r:httpd_t:s0"
    • The SELinux context of the process that attempted the denied action. In this case, it is the SELinux context of the Apache HTTP Server, which is running in the httpd_t domain.
  • tcontext="unconfined_u:object_r:samba_share_t:s0"
    • The SELinux context of the object (target) the process attempted to access. In this case, it is the SELinux context of file1. Note: the samba_share_t type is not accessible to processes running in the httpd_t domain.
  • From the system call (SYSCALL) message, two items are of interest:
    • success=no: indicates whether the denial (AVC) was enforced or not. success=no indicates the system call was not successful (SELinux denied access). success=yes indicates the system call was successful - this can be seen for permissive domains or unconfined domains, such as initrc_t and kernel_t.
    • exe="/usr/sbin/httpd": the full path to the executable that launched the process, which in this case, is exe="/usr/sbin/httpd".

Group   Configure auditd Data Retention   Group contains 6 rules

[ref]   The audit system writes data to /var/log/audit/audit.log. By default, auditd rotates 5 logs by size (6MB), retaining a maximum of 30MB of data in total, and refuses to write entries when the disk is too full. This minimizes the risk of audit data filling its partition and impacting other services. This also minimizes the risk of the audit daemon temporarily disabling the system if it cannot write audit log (which it can be configured to do). For a busy system or a system which is thoroughly auditing system activity, the default settings for data retention may be insufficient. The log file size needed will depend heavily on what types of events are being audited. First configure auditing to log all the events of interest. Then monitor the log size manually for awhile to determine what file size will allow you to keep the required data for the correct time period.

Using a dedicated partition for /var/log/audit prevents the auditd logs from disrupting system functionality if they fill, and, more importantly, prevents other activity in /var from filling the partition and stopping the audit trail. (The audit logs are size-limited and therefore unlikely to grow without bound unless configured to do so.) Some machines may have requirements that no actions occur which cannot be audited. If this is the case, then auditd can be configured to halt the machine if it runs out of space. Note: Since older logs are rotated, configuring auditd this way does not prevent older logs from being rotated away before they can be viewed. If your system is configured to halt when logging cannot be performed, make sure this can never happen under normal circumstances! Ensure that /var/log/audit is on its own partition, and that this partition is larger than the maximum amount of data auditd will retain normally.

Rule   Configure auditd flush priority   [ref]

The auditd service can be configured to synchronously write audit event data to disk. Add or correct the following line in /etc/audit/auditd.conf to ensure that audit event data is fully synchronized with the log files on the disk:

flush = incremental_async

Rationale:

Audit data should be synchronously written to disk to ensure log integrity. These parameters assure that all audit event data is fully synchronized with the log files on the disk.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82508-3

References:  1, 12, 13, 14, 15, 16, 2, 3, 5, 6, 7, 8, 9, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, BAI03.05, DSS01.03, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.3.1, CCI-001576, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.3.2.6.7, 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 6.1, SR 6.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.14.2.7, A.15.2.1, A.15.2.2, AU-11, CM-6(a), DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.PT-1, SRG-OS-000480-GPOS-00227

Rule   Write Audit Logs to the Disk   [ref]

To configure Audit daemon to write Audit logs to the disk, set write_logs to yes in /etc/audit/auditd.conf. This is the default setting.

Rationale:

If write_logs isn't set to yes, the Audit logs will not be written to the disk.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82510-9

References:  FAU_GEN.1.1.c, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/audit/auditd.conf" ] ; then
    LC_ALL=C sed -i "/^\s*write_logs\s*=\s*/Id" "/etc/audit/auditd.conf"
else
    touch "/etc/audit/auditd.conf"
fi
cp "/etc/audit/auditd.conf" "/etc/audit/auditd.conf.bak"
# Insert at the end of the file
printf '%s\n' "write_logs = yes" >> "/etc/audit/auditd.conf"
# Clean up after ourselves.
rm "/etc/audit/auditd.conf.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Write Audit Logs to the Disk
  block:

    - name: Deduplicate values from /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: false
        regexp: (?i)^\s*write_logs\s*=\s*
        state: absent

    - name: Insert correct line to /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: true
        line: write_logs = yes
        state: present
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - auditd_write_logs
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82510-9

Rule   Set hostname as computer node name in audit logs   [ref]

To configure Audit daemon to use value returned by gethostname syscall as computer node name in the audit events, set name_format to hostname in /etc/audit/auditd.conf.

Rationale:

If option name_format is left at its default value of none, audit events from different computers may be hard to distinguish.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82513-3

References:  CCI-001851, FAU_GEN.1, SRG-OS-000039-GPOS-00017, SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/audit/auditd.conf" ] ; then
    LC_ALL=C sed -i "/^\s*name_format\s*=\s*/Id" "/etc/audit/auditd.conf"
else
    touch "/etc/audit/auditd.conf"
fi
cp "/etc/audit/auditd.conf" "/etc/audit/auditd.conf.bak"
# Insert at the end of the file
printf '%s\n' "name_format = hostname" >> "/etc/audit/auditd.conf"
# Clean up after ourselves.
rm "/etc/audit/auditd.conf.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Set hostname as computer node name in audit logs
  block:

    - name: Deduplicate values from /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: false
        regexp: (?i)^\s*name_format\s*=\s*
        state: absent

    - name: Insert correct line to /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: true
        line: name_format = hostname
        state: present
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - auditd_name_format
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82513-3

Rule   Include Local Events in Audit Logs   [ref]

To configure Audit daemon to include local events in Audit logs, set local_events to yes in /etc/audit/auditd.conf. This is the default setting.

Rationale:

If option local_events isn't set to yes only events from network will be aggregated.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82509-1

References:  FAU_GEN.1.1.c, SRG-OS-000062-GPOS-00031

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/audit/auditd.conf" ] ; then
    LC_ALL=C sed -i "/^\s*local_events\s*=\s*/Id" "/etc/audit/auditd.conf"
else
    touch "/etc/audit/auditd.conf"
fi
cp "/etc/audit/auditd.conf" "/etc/audit/auditd.conf.bak"
# Insert at the end of the file
printf '%s\n' "local_events = yes" >> "/etc/audit/auditd.conf"
# Clean up after ourselves.
rm "/etc/audit/auditd.conf.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Include Local Events in Audit Logs
  block:

    - name: Deduplicate values from /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: false
        regexp: (?i)^\s*local_events\s*=\s*
        state: absent

    - name: Insert correct line to /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: true
        line: local_events = yes
        state: present
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - auditd_local_events
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82509-1

Rule   Set number of records to cause an explicit flush to audit logs   [ref]

To configure Audit daemon to issue an explicit flush to disk command after writing 50 records, set freq to 50 in /etc/audit/auditd.conf.

Rationale:

If option freq isn't set to 50, the flush to disk may happen after higher number of records, increasing the danger of audit loss.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82512-5

References:  FAU_GEN.1, SRG-OS-000051-GPOS-00024

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/audit/auditd.conf" ] ; then
    LC_ALL=C sed -i "/^\s*freq\s*=\s*/Id" "/etc/audit/auditd.conf"
else
    touch "/etc/audit/auditd.conf"
fi
cp "/etc/audit/auditd.conf" "/etc/audit/auditd.conf.bak"
# Insert at the end of the file
printf '%s\n' "freq = 50" >> "/etc/audit/auditd.conf"
# Clean up after ourselves.
rm "/etc/audit/auditd.conf.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Set number of records to cause an explicit flush to audit logs
  block:

    - name: Deduplicate values from /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: false
        regexp: (?i)^\s*freq\s*=\s*
        state: absent

    - name: Insert correct line to /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: true
        line: freq = 50
        state: present
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - auditd_freq
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82512-5

Rule   Resolve information before writing to audit logs   [ref]

To configure Audit daemon to resolve all uid, gid, syscall, architecture, and socket address information before writing the events to disk, set log_format to ENRICHED in /etc/audit/auditd.conf.

Rationale:

If option log_format isn't set to ENRICHED, the audit records will be stored in a format exactly as the kernel sends them.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82511-7

References:  FAU_GEN.1, SRG-OS-000255-GPOS-00096

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/audit/auditd.conf" ] ; then
    LC_ALL=C sed -i "/^\s*log_format\s*=\s*/Id" "/etc/audit/auditd.conf"
else
    touch "/etc/audit/auditd.conf"
fi
cp "/etc/audit/auditd.conf" "/etc/audit/auditd.conf.bak"
# Insert at the end of the file
printf '%s\n' "log_format = ENRICHED" >> "/etc/audit/auditd.conf"
# Clean up after ourselves.
rm "/etc/audit/auditd.conf.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Resolve information before writing to audit logs
  block:

    - name: Deduplicate values from /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: false
        regexp: (?i)^\s*log_format\s*=\s*
        state: absent

    - name: Insert correct line to /etc/audit/auditd.conf
      lineinfile:
        path: /etc/audit/auditd.conf
        create: true
        line: log_format = ENRICHED
        state: present
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - auditd_log_format
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82511-7
Group   Configure auditd Rules for Comprehensive Auditing   Group contains 5 groups and 21 rules

[ref]   The auditd program can perform comprehensive monitoring of system activity. This section describes recommended configuration settings for comprehensive auditing, but a full description of the auditing system's capabilities is beyond the scope of this guide. The mailing list linux-audit@redhat.com exists to facilitate community discussion of the auditing system.

The audit subsystem supports extensive collection of events, including:

  • Tracing of arbitrary system calls (identified by name or number) on entry or exit.
  • Filtering by PID, UID, call success, system call argument (with some limitations), etc.
  • Monitoring of specific files for modifications to the file's contents or metadata.

Auditing rules at startup are controlled by the file /etc/audit/audit.rules. Add rules to it to meet the auditing requirements for your organization. Each line in /etc/audit/audit.rules represents a series of arguments that can be passed to auditctl and can be individually tested during runtime. See documentation in /usr/share/doc/audit-VERSION and in the related man pages for more details.

If copying any example audit rulesets from /usr/share/doc/audit-VERSION, be sure to comment out the lines containing arch= which are not appropriate for your system's architecture. Then review and understand the following rules, ensuring rules are activated as needed for the appropriate architecture.

After reviewing all the rules, reading the following sections, and editing as needed, the new rules can be activated as follows:
$ sudo service auditd restart

Group   Record Information on Kernel Modules Loading and Unloading   Group contains 1 rule

[ref]   To capture kernel module loading and unloading events, use following lines, setting ARCH to either b32 for 32-bit system, or having two lines for both b32 and b64 in case your system is 64-bit:

-a always,exit -F arch=ARCH -S init_module,delete_module -F key=modules
Place to add the lines depends on a way auditd daemon is configured. If it is configured to use the augenrules program (the default), add the lines to a file with suffix .rules in the directory /etc/audit/rules.d. If the auditd daemon is configured to use the auditctl utility, add the lines to file /etc/audit/audit.rules.

Rule   Ensure auditd Collects Information on Kernel Module Loading and Unloading   [ref]

To capture kernel module loading and unloading events, use following lines, setting ARCH to either b32 for 32-bit system, or having two lines for both b32 and b64 in case your system is 64-bit:


-a always,exit -F arch=ARCH -S init_module,finit_module,delete_module -F key=modules

The place to add the lines depends on a way auditd daemon is configured. If it is configured to use the augenrules program (the default), add the lines to a file with suffix .rules in the directory /etc/audit/rules.d. If the auditd daemon is configured to use the auditctl utility, add the lines to file /etc/audit/audit.rules.

Rationale:

The addition/removal of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel.

Severity: 
medium
Identifiers and References

References:  5.2.17, 1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000172, 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.2.7

Group   Record Attempts to Alter Logon and Logout Events   Group contains 4 rules
Group   Records Events that Modify Date and Time Information   Group contains 5 rules

[ref]   Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time. All changes to the system time should be audited.

Rule   Record Attempts to Alter Time Through stime   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d for both 32 bit and 64 bit systems:

-a always,exit -F arch=b32 -S stime -F key=audit_time_rules
Since the 64 bit version of the "stime" system call is not defined in the audit lookup table, the corresponding "-F arch=b64" form of this rule is not expected to be defined on 64 bit systems (the aforementioned "-F arch=b32" stime rule form itself is sufficient for both 32 bit and 64 bit systems). If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file for both 32 bit and 64 bit systems:
-a always,exit -F arch=b32 -S stime -F key=audit_time_rules
Since the 64 bit version of the "stime" system call is not defined in the audit lookup table, the corresponding "-F arch=b64" form of this rule is not expected to be defined on 64 bit systems (the aforementioned "-F arch=b32" stime rule form itself is sufficient for both 32 bit and 64 bit systems). The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined system calls:
-a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules

Rationale:

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82617-2

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-001487, CCI-000169, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.4.2.b

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Perform remediation of Audit rules for stime syscall for x86 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - stime

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b32_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b32_rules_d="{{ audit_syscalls_found_b32_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key audit_time_rules
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)audit_time_rules$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/audit_time_rules.rules as the recipient for the
        rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/audit_time_rules.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - stime

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b32_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b32_audit_rules="{{ audit_syscalls_found_b32_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_audit_rules < audit_syscalls_number_of_syscalls
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_stime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82617-2
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

Rule   Record attempts to alter time through settimeofday   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F arch=b32 -S settimeofday -F key=audit_time_rules
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S settimeofday -F key=audit_time_rules
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-a always,exit -F arch=b32 -S settimeofday -F key=audit_time_rules
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S settimeofday -F key=audit_time_rules
The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:
-a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules

Rationale:

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82616-4

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-001487, CCI-000169, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.4.2.b

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Set architecture for audit tasks
  set_fact:
    audit_arch: b{{ ansible_architecture | regex_replace('.*(\d\d$)','\1') }}
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_settimeofday
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82616-4
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Perform remediation of Audit rules for settimeofday for x86 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - settimeofday

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b32_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b32_rules_d="{{ audit_syscalls_found_b32_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key audit_time_rules
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)audit_time_rules$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/audit_time_rules.rules as the recipient for the
        rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/audit_time_rules.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - settimeofday

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b32_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b32_audit_rules="{{ audit_syscalls_found_b32_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_audit_rules < audit_syscalls_number_of_syscalls
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_settimeofday
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82616-4
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Perform remediation of Audit rules for settimeofday for x86_64 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - settimeofday

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b64 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b64[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b64_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b64 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b64_rules_d="{{ audit_syscalls_found_b64_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key audit_time_rules
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)audit_time_rules$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/audit_time_rules.rules as the recipient for the
        rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/audit_time_rules.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b64"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b64_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b64_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - settimeofday

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b64 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b64[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b64_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b64 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b64_audit_rules="{{ audit_syscalls_found_b64_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b64"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b64_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b64_audit_rules < audit_syscalls_number_of_syscalls
  when:
    - audit_arch == "b64"
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_settimeofday
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82616-4
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

Rule   Record Attempts to Alter the localtime File   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-w /etc/localtime -p wa -k audit_time_rules
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-w /etc/localtime -p wa -k audit_time_rules
The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport and should always be used.

Rationale:

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82618-0

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-001487, CCI-000169, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.4.2.b

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Check if watch rule for /etc/localtime already exists in /etc/audit/rules.d/
  find:
    paths: /etc/audit/rules.d
    contains: ^\s*-w\s+/etc/localtime\s+-p\s+wa(\s|$)+
    patterns: '*.rules'
  register: find_existing_watch_rules_d
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Search /etc/audit/rules.d for other rules with specified key audit_time_rules
  find:
    paths: /etc/audit/rules.d
    contains: ^.*(?:-F key=|-k\s+)audit_time_rules$
    patterns: '*.rules'
  register: find_watch_key
  when:
    - find_existing_watch_rules_d.matched is defined and find_existing_watch_rules_d.matched
      == 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Use /etc/audit/rules.d/audit_time_rules.rules as the recipient for the rule
  set_fact:
    all_files:
      - /etc/audit/rules.d/audit_time_rules.rules
  when:
    - find_watch_key.matched is defined and find_watch_key.matched == 0 and find_existing_watch_rules_d.matched
      is defined and find_existing_watch_rules_d.matched == 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Use matched file as the recipient for the rule
  set_fact:
    all_files:
      - '{{ find_watch_key.files | map(attribute=''path'') | list | first }}'
  when:
    - find_watch_key.matched is defined and find_watch_key.matched > 0 and find_existing_watch_rules_d.matched
      is defined and find_existing_watch_rules_d.matched == 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Add watch rule for /etc/localtime in /etc/audit/rules.d/
  lineinfile:
    path: '{{ all_files[0] }}'
    line: -w /etc/localtime -p wa -k audit_time_rules
    create: true
  when:
    - find_existing_watch_rules_d.matched is defined and find_existing_watch_rules_d.matched
      == 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Check if watch rule for /etc/localtime already exists in /etc/audit/audit.rules
  find:
    paths: /etc/audit/
    contains: ^\s*-w\s+/etc/localtime\s+-p\s+wa(\s|$)+
    patterns: audit.rules
  register: find_existing_watch_audit_rules
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Add watch rule for /etc/localtime in /etc/audit/audit.rules
  lineinfile:
    line: -w /etc/localtime -p wa -k audit_time_rules
    state: present
    dest: /etc/audit/audit.rules
    create: true
  when:
    - find_existing_watch_audit_rules.matched is defined and find_existing_watch_audit_rules.matched
      == 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_watch_localtime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82618-0
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

Rule   Record Attempts to Alter Time Through clock_settime   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-change
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-change
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-change
The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:
-a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules

Rationale:

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82615-6

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-001487, CCI-000169, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.4.2.b

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Set architecture for audit tasks
  set_fact:
    audit_arch: b{{ ansible_architecture | regex_replace('.*(\d\d$)','\1') }}
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_clock_settime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82615-6
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Perform remediation of Audit rules for clock_settime for x86 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - clock_settime

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(?:-F[\s]+a0=0x0[\s]+)(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b32_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b32_rules_d="{{ audit_syscalls_found_b32_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key time-change
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)time-change$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/time-change.rules as the recipient for the rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/time-change.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -F a0=0x0 -k time-change' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - clock_settime

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(?:-F[\s]+a0=0x0[\s]+)(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b32_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b32_audit_rules="{{ audit_syscalls_found_b32_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -F a0=0x0 -k time-change' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_audit_rules < audit_syscalls_number_of_syscalls
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_clock_settime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82615-6
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Perform remediation of Audit rules for clock_settime for x86_64 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - clock_settime

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b64 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b64[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(?:-F[\s]+a0=0x0[\s]+)(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b64_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b64 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b64_rules_d="{{ audit_syscalls_found_b64_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key time-change
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)time-change$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/time-change.rules as the recipient for the rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/time-change.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b64"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b64_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -F a0=0x0 -k time-change' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b64_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - clock_settime

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b64 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b64[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(?:-F[\s]+a0=0x0[\s]+)(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b64_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b64 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b64_audit_rules="{{ audit_syscalls_found_b64_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b64"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b64_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -F a0=0x0 -k time-change' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b64_audit_rules < audit_syscalls_number_of_syscalls
  when:
    - audit_arch == "b64"
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_clock_settime
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82615-6
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

Rule   Record attempts to alter time through adjtimex   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F arch=b32 -S adjtimex -F key=audit_time_rules
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S adjtimex -F key=audit_time_rules
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-a always,exit -F arch=b32 -S adjtimex -F key=audit_time_rules
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S adjtimex -F key=audit_time_rules
The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:
-a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules

Rationale:

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82614-9

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-001487, CCI-000169, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.4.2.b

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Set architecture for audit tasks
  set_fact:
    audit_arch: b{{ ansible_architecture | regex_replace('.*(\d\d$)','\1') }}
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_adjtimex
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82614-9
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Perform remediation of Audit rules for adjtimex for x86 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - adjtimex

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b32_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b32_rules_d="{{ audit_syscalls_found_b32_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key audit_time_rules
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)audit_time_rules$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/audit_time_rules.rules as the recipient for the
        rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/audit_time_rules.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - adjtimex

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b32 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b32[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b32_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b32 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b32_audit_rules="{{ audit_syscalls_found_b32_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b32"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b32_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b32_audit_rules < audit_syscalls_number_of_syscalls
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_adjtimex
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82614-9
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Perform remediation of Audit rules for adjtimex for x86_64 platform
  block:

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - adjtimex

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b64 in /etc/audit/rules.d/
      find:
        paths: /etc/audit/rules.d
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b64[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: '*.rules'
      register: audit_syscalls_found_b64_rules_d
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b64 in /etc/audit/rules.d/
      set_fact: audit_syscalls_matched_b64_rules_d="{{ audit_syscalls_found_b64_rules_d.results|sum(attribute='matched')|int
        }}"

    - name: Search /etc/audit/rules.d for other rules with the key audit_time_rules
      find:
        paths: /etc/audit/rules.d
        contains: ^.*(?:-F key=|-k\s+)audit_time_rules$
        patterns: '*.rules'
      register: find_syscalls_files

    - name: Use /etc/audit/rules.d/audit_time_rules.rules as the recipient for the
        rule
      set_fact:
        all_files:
          - /etc/audit/rules.d/audit_time_rules.rules
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        == 0

    - name: Use matched file as the recipient for the rule
      set_fact:
        all_files:
          - '{{ find_syscalls_files.files | map(attribute=''path'') | list | first
            }}'
      when: find_syscalls_files.matched is defined and find_syscalls_files.matched
        > 0

    - name: Insert the syscall rule in {{ all_files[0] }}
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b64"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b64_rules_d.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in {{ all_files[0] }}
          lineinfile:
            path: '{{ all_files[0] }}'
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b64_rules_d < audit_syscalls_number_of_syscalls

    - name: Declare list of syscals
      set_fact:
        syscalls:
          - adjtimex

    - name: Declare number of syscalls
      set_fact: audit_syscalls_number_of_syscalls="{{ syscalls|length|int }}"

    - name: Check existence of syscalls for architecture b64 in /etc/audit/audit.rules
      find:
        paths: /etc/audit
        contains: ^[\s]*-a[\s]+always,exit[\s]+(?:.*-F[\s]+arch=b64[\s]+)(?:.*(-S[\s]+{{
          item }}[\s]+|([\s]+|[,]){{ item }}([\s]+|[,]))).*(-k[\s]+|-F[\s]+key=)[\S]+[\s]*$
        patterns: audit.rules
      register: audit_syscalls_found_b64_audit_rules
      loop: '{{ syscalls }}'

    - name: Get number of matched syscalls for architecture b64 in /etc/audit/audit.rules
      set_fact: audit_syscalls_matched_b64_audit_rules="{{ audit_syscalls_found_b64_audit_rules.results|sum(attribute='matched')|int
        }}"

    - name: Insert the syscall rule in /etc/audit/audit.rules
      block:

        - name: 'Construct rule: add rule list, action and arch'
          set_fact: tmpline="-a always,exit -F arch=b64"

        - name: 'Construct rule: add syscalls'
          set_fact: tmpline="{{ tmpline + ' -S ' + item.item }}"
          loop: '{{ audit_syscalls_found_b64_audit_rules.results }}'
          when: item.matched is defined and item.matched == 0

        - name: 'Construct rule: add fields and key'
          set_fact: tmpline="{{ tmpline + ' -k audit_time_rules' }}"

        - name: Insert the line in /etc/audit/audit.rules
          lineinfile:
            path: /etc/audit/audit.rules
            line: '{{ tmpline }}'
            create: true
            state: present
      when: audit_syscalls_matched_b64_audit_rules < audit_syscalls_number_of_syscalls
  when:
    - audit_arch == "b64"
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_time_adjtimex
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82614-9
    - PCI-DSS-Req-10.4.2.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1
Group   Record Events that Modify the System's Discretionary Access Controls   Group contains 2 rules

[ref]   At a minimum, the audit system should collect file permission changes for all users and root. Note that the "-F arch=b32" lines should be present even on a 64 bit system. These commands identify system calls for auditing. Even if the system is 64 bit it can still execute 32 bit system calls. Additionally, these rules can be configured in a number of ways while still achieving the desired effect. An example of this is that the "-S" calls could be split up and placed on separate lines, however, this is less efficient. Add the following to /etc/audit/audit.rules:

-a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=unset -F key=perm_mod
    -a always,exit -F arch=b32 -S chown,fchown,fchownat,lchown -F auid>=1000 -F auid!=unset -F key=perm_mod
    -a always,exit -F arch=b32 -S setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod
If your system is 64 bit then these lines should be duplicated and the arch=b32 replaced with arch=b64 as follows:
-a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>=1000 -F auid!=unset -F key=perm_mod
    -a always,exit -F arch=b64 -S chown,fchown,fchownat,lchown -F auid>=1000 -F auid!=unset -F key=perm_mod
    -a always,exit -F arch=b64 -S setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F auid>=1000 -F auid!=unset -F key=perm_mod

Rule   Record Events that Modify the System's Discretionary Access Controls - chown   [ref]

At a minimum, the audit system should collect file permission changes for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F arch=b32 -S chown -F auid>=1000 -F auid!=unset -F key=perm_mod
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S chown -F auid>=1000 -F auid!=unset -F key=perm_mod
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-a always,exit -F arch=b32 -S chown -F auid>=1000 -F auid!=unset -F key=perm_mod
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S chown -F auid>=1000 -F auid!=unset -F key=perm_mod

Warning:  Note that these rules can be configured in a number of ways while still achieving the desired effect. Here the system calls have been placed independent of other system calls. Grouping these system calls with others as identifying earlier in this guide is more efficient.
Rationale:

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82557-0

References:  5.2.10, 1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000126, CCI-000172, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, FAU_GEN.1.1.c, Req-10.5.5, SRG-OS-000064-GPOS-00033, SRG-OS-000392-GPOS-00172, SRG-OS-000458-GPOS-00203, SRG-OS-000474-GPOS-00219, SRG-OS-000458-VMM-001810, SRG-OS-000474-VMM-001940

Rule   Record Events that Modify the System's Discretionary Access Controls - chmod   [ref]

At a minimum, the audit system should collect file permission changes for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F arch=b32 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_mod
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_mod
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-a always,exit -F arch=b32 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_mod
If the system is 64 bit then also add the following line:
-a always,exit -F arch=b64 -S chmod -F auid>=1000 -F auid!=unset -F key=perm_mod

Warning:  Note that these rules can be configured in a number of ways while still achieving the desired effect. Here the system calls have been placed independent of other system calls. Grouping these system calls with others as identifying earlier in this guide is more efficient.
Rationale:

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82556-2

References:  5.2.10, 1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000126, CCI-000172, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, FAU_GEN.1.1.c, Req-10.5.5, SRG-OS-000064-GPOS-00033, SRG-OS-000392-GPOS-00172, SRG-OS-000458-GPOS-00203, SRG-OS-000458-VMM-001810, SRG-OS-000474-VMM-001940

Group   Record Execution Attempts to Run SELinux Privileged Commands   Group contains 6 rules

[ref]   At a minimum, the audit system should collect the execution of SELinux privileged commands for all users and root.

Rule   Record Any Attempts to Run seunshare   [ref]

At a minimum, the audit system should collect any execution attempt of the seunshare command for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file:
-a always,exit -F path=/usr/sbin/seunshare -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change

Rationale:

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider and advanced persistent threast.

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82574-5

References:  CCI-000172, AU-2(d), AU-12(c), AC-6(9), CM-6(a), FAU_GEN.1.1.c, SRG-OS-000463-VMM-001850

Rule   Record Any Attempts to Run setfiles   [ref]

At a minimum, the audit system should collect any execution attempt of the setfiles command for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F path=/usr/sbin/setfiles -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file:
-a always,exit -F path=/usr/sbin/setfiles -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change

Rationale:

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider and advanced persistent threast.

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82572-9

References:  CCI-000172, CCI-002884, AU-2(d), AU-12(c), AC-6(9), CM-6(a), SRG-OS-000392-GPOS-00172, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209, SRG-OS-000463-VMM-001850

Rule   Record Any Attempts to Run setsebool   [ref]

At a minimum, the audit system should collect any execution attempt of the setsebool command for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F path=/usr/sbin/setsebool -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file:
-a always,exit -F path=/usr/sbin/setsebool -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change

Rationale:

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider and advanced persistent threast.

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82573-7

References:  1, 12, 13, 14, 15, 16, 2, 3, 5, 6, 7, 8, 9, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, BAI03.05, DSS01.03, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000172, CCI-002884, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.3.2.6.7, 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 6.1, SR 6.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.14.2.7, A.15.2.1, A.15.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.PT-1, FAU_GEN.1.1.c, SRG-OS-000392-GPOS-00172, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209, SRG-OS-000463-VMM-001850

Rule   Record Any Attempts to Run semanage   [ref]

At a minimum, the audit system should collect any execution attempt of the semanage command for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F path=/usr/sbin/semanage -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file:
-a always,exit -F path=/usr/sbin/semanage -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change

Rationale:

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider and advanced persistent threast.

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82571-1

References:  1, 12, 13, 14, 15, 16, 2, 3, 5, 6, 7, 8, 9, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, BAI03.05, DSS01.03, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000172, CCI-002884, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.3.2.6.7, 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 6.1, SR 6.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.14.2.7, A.15.2.1, A.15.2.2, AC-2(4), AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.PT-1, FAU_GEN.1.1.c, SRG-OS-000392-GPOS-00172, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209, SRG-OS-000463-VMM-001850

Rule   Record Any Attempts to Run chcon   [ref]

At a minimum, the audit system should collect any execution attempt of the chcon command for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file:
-a always,exit -F path=/usr/bin/chcon -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change

Rationale:

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider and advanced persistent threast.

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82569-5

References:  1, 12, 13, 14, 15, 16, 2, 3, 5, 6, 7, 8, 9, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, BAI03.05, DSS01.03, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000172, CCI-002884, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.3.2.6.7, 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 6.1, SR 6.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.14.2.7, A.15.2.1, A.15.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.PT-1, FAU_GEN.1.1.c, SRG-OS-000392-GPOS-00172, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209, SRG-OS-000463-VMM-001850

Rule   Record Any Attempts to Run restorecon   [ref]

At a minimum, the audit system should collect any execution attempt of the restorecon command for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d:

-a always,exit -F path=/usr/sbin/restorecon -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file:
-a always,exit -F path=/usr/sbin/restorecon -F perm=x -F auid>=1000 -F auid!=unset -F key=privileged-priv_change

Rationale:

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider and advanced persistent threast.

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82570-3

References:  1, 12, 13, 14, 15, 16, 2, 3, 5, 6, 7, 8, 9, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, BAI03.05, DSS01.03, DSS03.05, DSS05.02, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000172, CCI-002884, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.3.2.6.7, 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 6.1, SR 6.2, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.14.2.7, A.15.2.1, A.15.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.PT-1, FAU_GEN.1.1.c, SRG-OS-000392-GPOS-00172, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209, SRG-OS-000463-VMM-001850

Rule   Ensure auditd Collects System Administrator Actions   [ref]

At a minimum, the audit system should collect administrator actions for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d:

-w /etc/sudoers -p wa -k actions
-w /etc/sudoers.d/ -p wa -k actions
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file:
-w /etc/sudoers -p wa -k actions
-w /etc/sudoers.d/ -p wa -k actions

Rationale:

The actions taken by system administrators should be audited to keep a record of what was executed on the system, as well as, for accountability purposes.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82613-1

References:  1, 11, 12, 13, 14, 15, 16, 18, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, DSS06.03, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000126, CCI-000130, CCI-000135, CCI-000172, CCI-002884, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.2.2, 4.3.3.3.9, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.8, 4.3.3.6.6, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, 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 2.1, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, 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-2(7)(b), AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-1, PR.AC-3, PR.AC-4, PR.AC-6, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, FAU_GEN.1.1.c, Req-10.2.2, Req-10.2.5.b, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000462-VMM-001840, SRG-OS-000471-VMM-001910

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Search /etc/audit/rules.d for audit rule entries for sysadmin actions
  find:
    paths: /etc/audit/rules.d
    recurse: false
    contains: ^.*/etc/sudoers.*$
    patterns: '*.rules'
  register: find_audit_sysadmin_actions
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Use /etc/audit/rules.d/actions.rules as the recipient for the rule
  set_fact:
    all_sysadmin_actions_files:
      - /etc/audit/rules.d/actions.rules
  when:
    - find_audit_sysadmin_actions.matched is defined and find_audit_sysadmin_actions.matched
      == 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Use matched file as the recipient for the rule
  set_fact:
    all_sysadmin_actions_files:
      - '{{ find_audit_sysadmin_actions.files | map(attribute=''path'') | list | first
        }}'
  when:
    - find_audit_sysadmin_actions.matched is defined and find_audit_sysadmin_actions.matched
      > 0
    - ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Inserts/replaces audit rule for /etc/sudoers rule in rules.d
  lineinfile:
    path: '{{ all_sysadmin_actions_files[0] }}'
    line: -w /etc/sudoers -p wa -k actions
    create: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Inserts/replaces audit rule for /etc/sudoers.d rule in rules.d
  lineinfile:
    path: '{{ all_sysadmin_actions_files[0] }}'
    line: -w /etc/sudoers.d/ -p wa -k actions
    create: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Inserts/replaces audit rule for /etc/sudoers in audit.rules
  lineinfile:
    path: /etc/audit/audit.rules
    line: -w /etc/sudoers -p wa -k actions
    create: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

- name: Inserts/replaces audit rule for /etc/sudoers.d in audit.rules
  lineinfile:
    path: /etc/audit/audit.rules
    line: -w /etc/sudoers.d/ -p wa -k actions
    create: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - audit_rules_sysadmin_actions
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82613-1
    - PCI-DSS-Req-10.2.2
    - PCI-DSS-Req-10.2.5.b
    - NIST-800-171-3.1.7
    - NIST-800-53-AC-2(7)(b)
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1

Rule   Record Events that Modify the System's Network Environment   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d, setting ARCH to either b32 or b64 as appropriate for your system:

-a always,exit -F arch=ARCH -S sethostname,setdomainname -F key=audit_rules_networkconfig_modification
-w /etc/issue -p wa -k audit_rules_networkconfig_modification
-w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
-w /etc/hosts -p wa -k audit_rules_networkconfig_modification
-w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, setting ARCH to either b32 or b64 as appropriate for your system:
-a always,exit -F arch=ARCH -S sethostname,setdomainname -F key=audit_rules_networkconfig_modification
-w /etc/issue -p wa -k audit_rules_networkconfig_modification
-w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
-w /etc/hosts -p wa -k audit_rules_networkconfig_modification
-w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification

Rationale:

The network environment should not be modified by anything other than administrator action. Any change to network parameters should be audited.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82588-5

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, 164.308(a)(1)(ii)(D), 164.308(a)(3)(ii)(A), 164.308(a)(5)(ii)(C), 164.312(a)(2)(i), 164.312(b), 164.312(d), 164.312(e), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.5.5

Rule   Record Events that Modify User/Group Information   [ref]

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d, in order to capture events that modify account changes:

-w /etc/group -p wa -k audit_rules_usergroup_modification
-w /etc/passwd -p wa -k audit_rules_usergroup_modification
-w /etc/gshadow -p wa -k audit_rules_usergroup_modification
-w /etc/shadow -p wa -k audit_rules_usergroup_modification
-w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification

If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file, in order to capture events that modify account changes:
-w /etc/group -p wa -k audit_rules_usergroup_modification
-w /etc/passwd -p wa -k audit_rules_usergroup_modification
-w /etc/gshadow -p wa -k audit_rules_usergroup_modification
-w /etc/shadow -p wa -k audit_rules_usergroup_modification
-w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification

Warning:  This rule checks for multiple syscalls related to account changes; it was written with DISA STIG in mind. Other policies should use a separate rule for each syscall that needs to be checked. For example:
  • audit_rules_usergroup_modification_group
  • audit_rules_usergroup_modification_gshadow
  • audit_rules_usergroup_modification_passwd
Rationale:

In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy.

Severity: 
medium
Identifiers and References

References:  5.2.5, 1, 11, 12, 13, 14, 15, 16, 18, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, DSS06.03, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.1.7, CCI-000018, CCI-000130, CCI-000172, CCI-001403, CCI-002130, 4.2.3.10, 4.3.2.6.7, 4.3.3.2.2, 4.3.3.3.9, 4.3.3.5.1, 4.3.3.5.2, 4.3.3.5.8, 4.3.3.6.6, 4.3.3.7.2, 4.3.3.7.3, 4.3.3.7.4, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, 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 2.1, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, 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-2(4), AU-2(d), AU-12(c), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-1, PR.AC-3, PR.AC-4, PR.AC-6, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.2.5, SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000239-GPOS-00089, SRG-OS-000241-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000476-GPOS-00221

Rule   Enable auditd Service   [ref]

The auditd service is an essential userspace component of the Linux Auditing System, as it is responsible for writing audit records to disk. The auditd service can be enabled with the following command:

$ sudo systemctl enable auditd.service

Rationale:

Without establishing what type of events occurred, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. Ensuring the auditd service is active ensures audit records generated by the kernel are appropriately recorded.

Additionally, a properly configured audit subsystem ensures that actions of individual system users can be uniquely traced to those users so they can be held accountable for their actions.

Severity: 
high
Identifiers and References

Identifiers:  CCE-82463-1

References:  1, 11, 12, 13, 14, 15, 16, 19, 2, 3, 4, 5, 6, 7, 8, 9, 5.4.1.1, APO10.01, APO10.03, APO10.04, APO10.05, APO11.04, APO12.06, APO13.01, BAI03.05, BAI08.02, DSS01.03, DSS01.04, DSS02.02, DSS02.04, DSS02.07, DSS03.01, DSS03.05, DSS05.02, DSS05.03, DSS05.04, DSS05.05, DSS05.07, MEA01.01, MEA01.02, MEA01.03, MEA01.04, MEA01.05, MEA02.01, 3.3.1, 3.3.2, 3.3.6, CCI-000126, CCI-000130, CCI-000131, CCI-000132, CCI-000133, CCI-000134, CCI-000135, CCI-001464, CCI-001487, CCI-001814, 164.308(a)(1)(ii)(D), 164.308(a)(5)(ii)(C), 164.310(a)(2)(iv), 164.310(d)(2)(iii), 164.312(b), 4.2.3.10, 4.3.2.6.7, 4.3.3.3.9, 4.3.3.5.8, 4.3.3.6.6, 4.3.4.4.7, 4.3.4.5.6, 4.3.4.5.7, 4.3.4.5.8, 4.4.2.1, 4.4.2.2, 4.4.2.4, SR 1.13, SR 2.10, SR 2.11, SR 2.12, SR 2.6, 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 6.1, SR 6.2, SR 7.1, SR 7.6, A.11.2.6, A.12.4.1, A.12.4.2, A.12.4.3, A.12.4.4, A.12.7.1, A.13.1.1, A.13.2.1, A.14.1.3, A.14.2.7, A.15.2.1, A.15.2.2, A.16.1.4, A.16.1.5, A.16.1.7, A.6.2.1, A.6.2.2, AC-2(g), AU-3, AU-10, AU-2(d), AU-12(c), AU-14(1), AC-6(9), CM-6(a), DE.AE-3, DE.AE-5, DE.CM-1, DE.CM-3, DE.CM-7, ID.SC-4, PR.AC-3, PR.PT-1, PR.PT-4, RS.AN-1, RS.AN-4, Req-10.1, SRG-OS-000037-GPOS-00015, SRG-OS-000038-GPOS-00016, SRG-OS-000039-GPOS-00017, SRG-OS-000040-GPOS-00018, SRG-OS-000042-GPOS-00021, SRG-OS-000254-GPOS-00095, SRG-OS-000255-GPOS-00096, SRG-OS-000365-GPOS-00152, SRG-OS-000037-VMM-000150, SRG-OS-000063-VMM-000310, SRG-OS-000038-VMM-000160, SRG-OS-000039-VMM-000170, SRG-OS-000040-VMM-000180, SRG-OS-000041-VMM-000190

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
- name: Enable service auditd
  block:

    - name: Gather the package facts
      package_facts:
        manager: auto

    - name: Enable service auditd
      service:
        name: auditd
        enabled: 'yes'
        state: started
      when:
        - '"audit" in ansible_facts.packages'
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - service_auditd_enabled
    - high_severity
    - enable_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82463-1
    - PCI-DSS-Req-10.1
    - NIST-800-171-3.3.1
    - NIST-800-171-3.3.2
    - NIST-800-171-3.3.6
    - NIST-800-53-AC-2(g)
    - NIST-800-53-AU-3
    - NIST-800-53-AU-10
    - NIST-800-53-AU-2(d)
    - NIST-800-53-AU-12(c)
    - NIST-800-53-AU-14(1)
    - NIST-800-53-AC-6(9)
    - NIST-800-53-CM-6(a)
    - CJIS-5.4.1.1
Remediation Puppet snippet:   (show)

Complexity:low
Disruption:low
Strategy:enable
include enable_auditd

class enable_auditd {
  service {'auditd':
    enable => true,
    ensure => 'running',
  }
}
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    systemd:
      units:
      - name: auditd.service
        enabled: true
Group   SELinux   Group contains 2 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 OpenShift Container Platform 4, 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 OpenShift Container Platform 4 system, unless that system has unusual requirements which make a stronger policy appropriate.

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-82531-5

References:  NT28(R4), 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)(a), AU-9, SC-7(21), 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, SRG-OS-000445-VMM-001780

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-82532-3

References:  NT28(R66), 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)(a), AU-9, SC-7(21), 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, SRG-OS-000445-VMM-001780

Group   File Permissions and Masks   Group contains 2 groups and 7 rules

[ref]   Traditional Unix security relies heavily on file and directory permissions to prevent unauthorized users from reading or modifying files to which they should not have access.

Several of the commands in this section search filesystems for files or directories with certain characteristics, and are intended to be run on every local partition on a given system. When the variable PART appears in one of the commands below, it means that the command is intended to be run repeatedly, with the name of each local partition substituted for PART in turn.

The following command prints a list of all xfs partitions on the local system, which is the default filesystem for Red Hat OpenShift Container Platform 4 installations:

$ mount -t xfs | awk '{print $3}'
For any systems that use a different local filesystem type, modify this command as appropriate.

Group   Restrict Programs from Dangerous Execution Patterns   Group contains 1 group and 7 rules

[ref]   The recommendations in this section are designed to ensure that the system's features to protect against potentially dangerous program execution are activated. These protections are applied at the system initialization or kernel level, and defend against certain types of badly-configured or compromised programs.

Group   Enable ExecShield   Group contains 2 rules

[ref]   ExecShield describes kernel features that provide protection against exploitation of memory corruption errors such as buffer overflows. These features include random placement of the stack and other memory regions, prevention of execution in memory that should only hold data, and special handling of text buffers. These protections are enabled by default on 32-bit systems and controlled through sysctl variables kernel.exec-shield and kernel.randomize_va_space. On the latest 64-bit systems, kernel.exec-shield cannot be enabled or disabled with sysctl.

Rule   Restrict Exposed Kernel Pointer Addresses Access   [ref]

To set the runtime status of the kernel.kptr_restrict kernel parameter, run the following command:

$ sudo sysctl -w kernel.kptr_restrict=1
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
kernel.kptr_restrict = 1

Rationale:

Exposing kernel pointers (through procfs or seq_printf()) exposes kernel writeable structures that can contain functions pointers. If a write vulnereability occurs in the kernel allowing a write access to any of this structure, the kernel can be compromise. This option disallow any program withtout the CAP_SYSLOG capability from getting the kernel pointers addresses, replacing them with 0.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82498-7

References:  NT28(R23), SC-30, SC-30(2), SC-30(5), CM-6(a), SRG-OS-000132-GPOS-00067

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl kernel.kptr_restrict is set to 1
  sysctl:
    name: kernel.kptr_restrict
    value: '1'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_kernel_kptr_restrict
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - CCE-82498-7
    - NIST-800-53-SC-30
    - NIST-800-53-SC-30(2)
    - NIST-800-53-SC-30(5)
    - NIST-800-53-CM-6(a)
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,kernel.kptr_restrict%3D1
        filesystem: root
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_kernel_kptr_restrict.conf

Rule   Enable Randomized Layout of Virtual Address Space   [ref]

To set the runtime status of the kernel.randomize_va_space kernel parameter, run the following command:

$ sudo sysctl -w kernel.randomize_va_space=2
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
kernel.randomize_va_space = 2

Rationale:

Address space layout randomization (ASLR) makes it more difficult for an attacker to predict the location of attack code they have introduced into a process's address space during an attempt at exploitation. Additionally, ASLR makes it more difficult for an attacker to know the location of existing code in order to re-purpose it using return oriented programming (ROP) techniques.

Severity: 
medium
Identifiers and References

References:  NT28(R23), 3.1.7, CCI-000366, CCI-002824, 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), SC-30, SC-30(2), CM-6(a), SRG-OS-000433-GPOS-00193, SRG-OS-000480-GPOS-00227

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl kernel.randomize_va_space is set to 2
  sysctl:
    name: kernel.randomize_va_space
    value: '2'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_kernel_randomize_va_space
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - NIST-800-171-3.1.7
    - NIST-800-53-SC-30
    - NIST-800-53-SC-30(2)
    - NIST-800-53-CM-6(a)

Rule   Restrict usage of ptrace to descendant processes   [ref]

To set the runtime status of the kernel.yama.ptrace_scope kernel parameter, run the following command:

$ sudo sysctl -w kernel.yama.ptrace_scope=1
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
kernel.yama.ptrace_scope = 1

Rationale:

Unrestricted usage of ptrace allows compromised binaries to run ptrace on another processes of the user. Like this, the attacker can steal sensitive information from the target processes (e.g. SSH sessions, web browser, ...) without any additional assistance from the user (i.e. without resorting to phishing).

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82501-8

References:  NT28(R25), SRG-OS-000132-GPOS-00067

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl kernel.yama.ptrace_scope is set to 1
  sysctl:
    name: kernel.yama.ptrace_scope
    value: '1'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_kernel_yama_ptrace_scope
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - CCE-82501-8
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,kernel.yama.ptrace_scope%3D1
        filesystem: root
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_kernel_yama_ptrace_scope.conf

Rule   Disable Kernel Image Loading   [ref]

To set the runtime status of the kernel.kexec_load_disabled kernel parameter, run the following command:

$ sudo sysctl -w kernel.kexec_load_disabled=1
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
kernel.kexec_load_disabled = 1

Rationale:

Disabling kexec_load allows greater control of the kernel memory. It makes it impossible to load another kernel image after it has been disabled.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82500-0

References:  SRG-OS-000480-GPOS-00227

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl kernel.kexec_load_disabled is set to 1
  sysctl:
    name: kernel.kexec_load_disabled
    value: '1'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_kernel_kexec_load_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - CCE-82500-0
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,kernel.kexec_load_disabled%3D1
        filesystem: root
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_kernel_kexec_load_disabled.conf

Rule   Disable Access to Network bpf() Syscall From Unprivileged Processes   [ref]

To set the runtime status of the kernel.unprivileged_bpf_disabled kernel parameter, run the following command:

$ sudo sysctl -w kernel.unprivileged_bpf_disabled=1
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
kernel.unprivileged_bpf_disabled = 1

Rationale:

Loading and accessing the packet filters programs and maps using the bpf() syscall has the potential of revealing sensitive information about the kernel state.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82504-2

References:  FMT_SMF_EXT.1, SRG-OS-000132-GPOS-00067

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl kernel.unprivileged_bpf_disabled is set to 1
  sysctl:
    name: kernel.unprivileged_bpf_disabled
    value: '1'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_kernel_unprivileged_bpf_disabled
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - CCE-82504-2
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,kernel.unprivileged_bpf_disabled%3D1
        filesystem: root
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_kernel_unprivileged_bpf_disabled.conf

Rule   Harden the operation of the BPF just-in-time compiler   [ref]

To set the runtime status of the net.core.bpf_jit_harden kernel parameter, run the following command:

$ sudo sysctl -w net.core.bpf_jit_harden=2
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
net.core.bpf_jit_harden = 2

Rationale:

When hardened, the extended Berkeley Packet Filter just-in-time compiler will randomize any kernel addresses in the BPF programs and maps, and will not expose the JIT addresses in /proc/kallsyms.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82505-9

References:  FMT_SMF_EXT.1, SRG-OS-000480-GPOS-00227

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl net.core.bpf_jit_harden is set to 2
  sysctl:
    name: net.core.bpf_jit_harden
    value: '2'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_net_core_bpf_jit_harden
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - CCE-82505-9

Rule   Restrict Access to Kernel Message Buffer   [ref]

To set the runtime status of the kernel.dmesg_restrict kernel parameter, run the following command:

$ sudo sysctl -w kernel.dmesg_restrict=1
To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:
kernel.dmesg_restrict = 1

Rationale:

Unprivileged access to the kernel syslog can expose sensitive kernel address information.

Severity: 
medium
Identifiers and References

Identifiers:  CCE-82499-5

References:  NT28(R23), 3.1.5, CCI-001314, 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), SI-11(a), SI-11(b), SRG-OS-000132-GPOS-00067

Remediation Ansible snippet:   (show)

Complexity:low
Disruption:medium
Reboot:true
Strategy:disable
- name: Ensure sysctl kernel.dmesg_restrict is set to 1
  sysctl:
    name: kernel.dmesg_restrict
    value: '1'
    state: present
    reload: true
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sysctl_kernel_dmesg_restrict
    - medium_severity
    - disable_strategy
    - low_complexity
    - medium_disruption
    - reboot_required
    - CCE-82499-5
    - NIST-800-171-3.1.5
    - NIST-800-53-SI-11(a)
    - NIST-800-53-SI-11(b)
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,kernel.dmesg_restrict%3D1
        filesystem: root
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_kernel_dmesg_restrict.conf
Group   Installing and Maintaining Software   Group contains 2 groups and 2 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   System and Software Integrity   Group contains 1 group 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   System Cryptographic Policies   Group contains 2 rules

[ref]   Linux has the capability to centrally configure cryptographic polices. The command update-crypto-policies is used to set the policy applicable for the various cryptographic back-ends, such as SSL/TLS libraries. The configured cryptographic policies will be the default policy used by these backends unless the application user configures them otherwise. When the system has been configured to use the centralized cryptographic policies, the administrator is assured that any application that utilizes the supported backends will follow a policy that adheres to the configured profile. Currently the supported backends are:

  • GnuTLS library
  • OpenSSL library
  • NSS library
  • OpenJDK
  • Libkrb5
  • BIND
  • OpenSSH
Applications and languages which rely on any of these backends will follow the system policies as well. Examples are apache httpd, nginx, php, and others.

Rule   Configure System Cryptography Policy   [ref]

To configure the system cryptography policy to use ciphers only from the FUTURE policy, run the following command:

$ sudo update-crypto-policies --set FUTURE
The rule checks if settings for selected crypto policy are configured as expected. Configuration files in the /etc/crypto-policies/back-ends are either symlinks to correct files provided by Crypto-policies package or they are regular files in case crypto policy customizations are applied. Crypto policies may be customized by crypto policy modules, in which case it is delimited from the base policy using a colon.

Warning:  The system needs to be rebooted for these changes to take effect.
Warning:  System Crypto Modules must be provided by a vendor that undergoes FIPS-140 certifications. FIPS-140 is applicable to all Federal agencies that use cryptographic-based security systems to protect sensitive information in computer and telecommunication systems (including voice systems) as defined in Section 5131 of the Information Technology Management Reform Act of 1996, Public Law 104-106. This standard shall be used in designing and implementing cryptographic modules that Federal departments and agencies operate or are operated for them under contract. See https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.140-2.pdf To meet this, the system has to have cryptographic software provided by a vendor that has undergone this certification. This means providing documentation, test results, design information, and independent third party review by an accredited lab. While open source software is capable of meeting this, it does not meet FIPS-140 unless the vendor submits to this process.
Rationale:

Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data.

Severity: 
high
Identifiers and References

Identifiers:  CCE-82541-4

References:  AC-17(a), AC-17(2), CM-6(a), MA-4(6), SC-13, SC-12(2), SC-12(3), SRG-OS-000396-GPOS-00176, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174

Rule   Configure SSH to use System Crypto Policy   [ref]

Crypto Policies provide a centralized control over crypto algorithms usage of many packages. SSH is supported by crypto policy, but the SSH configuration may be set up to ignore it. To check that Crypto Policies settings are configured correctly, ensure that the CRYPTO_POLICY variable is either commented or not set at all in the /etc/sysconfig/sshd.

Rationale:

Overriding the system crypto policy makes the behavior of the SSH service violate expectations, and makes system configuration more fragmented.

Severity: 
medium
Identifiers and References

References:  AC-17(a), AC-17(2), CM-6(a), MA-4(6), SC-13

Group   Services   Group contains 2 groups and 10 rules

[ref]   The best protection against vulnerable software is running less software. This section describes how to review the software which Red Hat OpenShift Container Platform 4 installs on a system and disable software which is not needed. It then enumerates the software packages installed on a default Red Hat OpenShift Container Platform 4 system and provides guidance about which ones can be safely disabled.

Red Hat OpenShift Container Platform 4 provides a convenient minimal install option that essentially installs the bare necessities for a functional system. When building Red Hat OpenShift Container Platform 4 systems, it is highly recommended to select the minimal packages and then build up the system from there.

Group   SSH Server   Group contains 1 group and 10 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 10 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 to connect to systems if a cache of the remote systems public keys is 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

References:  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(a), CM-7(a), CM-7(b), CM-6(a), PR.IP-1, FIA_AFL.1, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*IgnoreUserKnownHosts\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "IgnoreUserKnownHosts yes" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "IgnoreUserKnownHosts yes" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable SSH Support for User Known Hosts
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*IgnoreUserKnownHosts\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: IgnoreUserKnownHosts yes
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_disable_user_known_hosts
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-171-3.1.12
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-7(a)
    - NIST-800-53-CM-7(b)
    - NIST-800-53-CM-6(a)
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

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

References:  NT007(R17), 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, CCI-000766, 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-17(a), CM-7(a), CM-7(b), CM-6(a), PR.AC-4, PR.AC-6, PR.DS-5, PR.IP-1, PR.PT-3, FIA_AFL.1, SRG-OS-000106-GPOS-00053, SRG-OS-000480-GPOS-00229, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*PermitEmptyPasswords\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "PermitEmptyPasswords no" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "PermitEmptyPasswords no" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable SSH Access via Empty Passwords
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*PermitEmptyPasswords\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: PermitEmptyPasswords no
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_disable_empty_passwords
    - high_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-171-3.1.1
    - NIST-800-171-3.1.5
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-7(a)
    - NIST-800-53-CM-7(b)
    - NIST-800-53-CM-6(a)
    - CJIS-5.5.6
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

Rule   Enable SSH Print Last Log   [ref]

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

PrintLastLog yes

Rationale:

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

Severity: 
medium
Identifiers and References

References:  1, 12, 15, 16, DSS05.04, DSS05.10, DSS06.10, CCI-000366, 4.3.3.6.1, 4.3.3.6.2, 4.3.3.6.3, 4.3.3.6.4, 4.3.3.6.5, 4.3.3.6.6, 4.3.3.6.7, 4.3.3.6.8, 4.3.3.6.9, SR 1.1, SR 1.10, SR 1.2, SR 1.5, SR 1.7, SR 1.8, SR 1.9, A.18.1.4, A.9.2.1, A.9.2.4, A.9.3.1, A.9.4.2, A.9.4.3, AC-9, AC-17(a), CM-6(a), PR.AC-7, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*PrintLastLog\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "PrintLastLog yes" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "PrintLastLog yes" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Enable SSH Print Last Log
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*PrintLastLog\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: PrintLastLog yes
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_print_last_log
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-53-AC-9
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-6(a)
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

Rule   Set LogLevel to INFO   [ref]

The INFO parameter specifices that record login and logout activity will be logged. To specify the log level in SSH, add or correct the following line in the /etc/ssh/sshd_config file:

LogLevel INFO

Rationale:

SSH provides several logging levels with varying amounts of verbosity. DEBUG is specifically not recommended other than strictly for debugging SSH communications since it provides so much data that it is difficult to identify important security information. INFO level is the basic level that only records login activity of SSH users. In many situations, such as Incident Response, it is important to determine when a particular user was active on a system. The logout record can eliminate those users who disconnected, which helps narrow the field.

Severity: 
low
Identifiers and References

References:  AC-17(a), CM-6(a)

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*LogLevel\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "LogLevel INFO" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "LogLevel INFO" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Set LogLevel to INFO
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*LogLevel\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: LogLevel INFO
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_set_loglevel_info
    - low_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-6(a)

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-82665-1

References:  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-17(a), CM-7(a), CM-7(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)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*IgnoreRhosts\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "IgnoreRhosts yes" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "IgnoreRhosts yes" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable SSH Support for .rhosts Files
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*IgnoreRhosts\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: IgnoreRhosts yes
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_disable_rhosts
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - CCE-82665-1
    - NIST-800-171-3.1.12
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-7(a)
    - NIST-800-53-CM-7(b)
    - NIST-800-53-CM-6(a)
    - CJIS-5.5.6
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

Rule   Do Not Allow SSH Environment Options   [ref]

To ensure users are not able to override environment variables of 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

References:  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(a), CM-7(a), CM-7(b), CM-6(a), PR.IP-1, SRG-OS-000480-GPOS-00229, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*PermitUserEnvironment\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "PermitUserEnvironment no" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "PermitUserEnvironment no" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Do Not Allow SSH Environment Options
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*PermitUserEnvironment\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: PermitUserEnvironment no
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_do_not_permit_user_env
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-171-3.1.12
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-7(a)
    - NIST-800-53-CM-7(b)
    - NIST-800-53-CM-6(a)
    - CJIS-5.5.6
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

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

References:  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(a), CM-6(a), PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*StrictModes\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "StrictModes yes" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "StrictModes yes" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Enable Use of Strict Mode Checking
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*StrictModes\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: StrictModes yes
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_enable_strictmodes
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-171-3.1.12
    - NIST-800-53-AC-6
    - NIST-800-53-AC-17(a)
    - NIST-800-53-CM-6(a)
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

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

References:  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, CM-6(a), AC-17(a), AC-6, PR.AC-4, PR.DS-5, SRG-OS-000480-GPOS-00227

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict

var_sshd_priv_separation="sandbox"

if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*UsePrivilegeSeparation\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "UsePrivilegeSeparation $var_sshd_priv_separation" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "UsePrivilegeSeparation $var_sshd_priv_separation" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Enable Use of Privilege Separation
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*UsePrivilegeSeparation\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: UsePrivilegeSeparation sandbox
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_use_priv_separation
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-171-3.1.12
    - NIST-800-53-CM-6(a)
    - NIST-800-53-AC-17(a)
    - NIST-800-53-AC-6
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: data:,%23%09%24OpenBSD%3A%20sshd_config%2Cv%201.103%202018/04/09%2020%3A41%3A22%20tj%20Exp%20%24%0A%0A%23%20This%20is%20the%20sshd%20server%20system-wide%20configuration%20file.%20%20See%0A%23%20sshd_config%285%29%20for%20more%20information.%0A%0A%23%20This%20sshd%20was%20compiled%20with%20PATH%3D/usr/local/bin%3A/usr/bin%3A/usr/local/sbin%3A/usr/sbin%0A%0A%23%20The%20strategy%20used%20for%20options%20in%20the%20default%20sshd_config%20shipped%20with%0A%23%20OpenSSH%20is%20to%20specify%20options%20with%20their%20default%20value%20where%0A%23%20possible%2C%20but%20leave%20them%20commented.%20%20Uncommented%20options%20override%20the%0A%23%20default%20value.%0A%0A%23%20If%20you%20want%20to%20change%20the%20port%20on%20a%20SELinux%20system%2C%20you%20have%20to%20tell%0A%23%20SELinux%20about%20this%20change.%0A%23%20semanage%20port%20-a%20-t%20ssh_port_t%20-p%20tcp%20%23PORTNUMBER%0A%23%0A%23Port%2022%0A%23AddressFamily%20any%0A%23ListenAddress%200.0.0.0%0A%23ListenAddress%20%3A%3A%0A%0AHostKey%20/etc/ssh/ssh_host_rsa_key%0AHostKey%20/etc/ssh/ssh_host_ecdsa_key%0AHostKey%20/etc/ssh/ssh_host_ed25519_key%0A%0A%23%20Ciphers%20and%20keying%0ARekeyLimit%20512M%201h%0A%0A%23%20System-wide%20Crypto%20policy%3A%0A%23%20This%20system%20is%20following%20system-wide%20crypto%20policy.%20The%20changes%20to%0A%23%20Ciphers%2C%20MACs%2C%20KexAlgoritms%20and%20GSSAPIKexAlgorithsm%20will%20not%20have%20any%0A%23%20effect%20here.%20They%20will%20be%20overridden%20by%20command-line%20options%20passed%20on%0A%23%20the%20server%20start%20up.%0A%23%20To%20opt%20out%2C%20uncomment%20a%20line%20with%20redefinition%20of%20%20CRYPTO_POLICY%3D%0A%23%20variable%20in%20%20/etc/sysconfig/sshd%20%20to%20overwrite%20the%20policy.%0A%23%20For%20more%20information%2C%20see%20manual%20page%20for%20update-crypto-policies%288%29.%0A%0A%23%20Logging%0A%23SyslogFacility%20AUTH%0ASyslogFacility%20AUTHPRIV%0A%23LogLevel%20INFO%0A%0A%23%20Authentication%3A%0A%0A%23LoginGraceTime%202m%0APermitRootLogin%20no%0AStrictModes%20yes%0A%23MaxAuthTries%206%0A%23MaxSessions%2010%0A%0APubkeyAuthentication%20yes%0A%0A%23%20The%20default%20is%20to%20check%20both%20.ssh/authorized_keys%20and%20.ssh/authorized_keys2%0A%23%20but%20this%20is%20overridden%20so%20installations%20will%20only%20check%20.ssh/authorized_keys%0AAuthorizedKeysFile%09.ssh/authorized_keys%0A%0A%23AuthorizedPrincipalsFile%20none%0A%0A%23AuthorizedKeysCommand%20none%0A%23AuthorizedKeysCommandUser%20nobody%0A%0A%23%20For%20this%20to%20work%20you%20will%20also%20need%20host%20keys%20in%20/etc/ssh/ssh_known_hosts%0AHostbasedAuthentication%20no%0A%23%20Change%20to%20yes%20if%20you%20don%27t%20trust%20~/.ssh/known_hosts%20for%0A%23%20HostbasedAuthentication%0AIgnoreUserKnownHosts%20yes%0A%23%20Don%27t%20read%20the%20user%27s%20~/.rhosts%20and%20~/.shosts%20files%0AIgnoreRhosts%20yes%0A%0A%23%20To%20disable%20tunneled%20clear%20text%20passwords%2C%20change%20to%20no%20here%21%0A%23PasswordAuthentication%20yes%0APermitEmptyPasswords%20no%0APasswordAuthentication%20no%0A%0A%23%20Change%20to%20no%20to%20disable%20s/key%20passwords%0A%23ChallengeResponseAuthentication%20yes%0AChallengeResponseAuthentication%20no%0A%0A%23%20Kerberos%20options%0AKerberosAuthentication%20no%0A%23KerberosOrLocalPasswd%20yes%0A%23KerberosTicketCleanup%20yes%0A%23KerberosGetAFSToken%20no%0A%23KerberosUseKuserok%20yes%0A%0A%23%20GSSAPI%20options%0AGSSAPIAuthentication%20no%0AGSSAPICleanupCredentials%20no%0A%23GSSAPIStrictAcceptorCheck%20yes%0A%23GSSAPIKeyExchange%20no%0A%23GSSAPIEnablek5users%20no%0A%0A%23%20Set%20this%20to%20%27yes%27%20to%20enable%20PAM%20authentication%2C%20account%20processing%2C%0A%23%20and%20session%20processing.%20If%20this%20is%20enabled%2C%20PAM%20authentication%20will%0A%23%20be%20allowed%20through%20the%20ChallengeResponseAuthentication%20and%0A%23%20PasswordAuthentication.%20%20Depending%20on%20your%20PAM%20configuration%2C%0A%23%20PAM%20authentication%20via%20ChallengeResponseAuthentication%20may%20bypass%0A%23%20the%20setting%20of%20%22PermitRootLogin%20without-password%22.%0A%23%20If%20you%20just%20want%20the%20PAM%20account%20and%20session%20checks%20to%20run%20without%0A%23%20PAM%20authentication%2C%20then%20enable%20this%20but%20set%20PasswordAuthentication%0A%23%20and%20ChallengeResponseAuthentication%20to%20%27no%27.%0A%23%20WARNING%3A%20%27UsePAM%20no%27%20is%20not%20supported%20in%20Fedora%20and%20may%20cause%20several%0A%23%20problems.%0AUsePAM%20yes%0A%0A%23AllowAgentForwarding%20yes%0A%23AllowTcpForwarding%20yes%0A%23GatewayPorts%20no%0AX11Forwarding%20yes%0A%23X11DisplayOffset%2010%0A%23X11UseLocalhost%20yes%0A%23PermitTTY%20yes%0A%0A%23%20It%20is%20recommended%20to%20use%20pam_motd%20in%20/etc/pam.d/sshd%20instead%20of%20PrintMotd%2C%0A%23%20as%20it%20is%20more%20configurable%20and%20versatile%20than%20the%20built-in%20version.%0APrintMotd%20no%0A%0APrintLastLog%20yes%0A%23TCPKeepAlive%20yes%0APermitUserEnvironment%20no%0ACompression%20no%0AClientAliveInterval%20600%0AClientAliveCountMax%200%0A%23UseDNS%20no%0A%23PidFile%20/var/run/sshd.pid%0A%23MaxStartups%2010%3A30%3A100%0A%23PermitTunnel%20no%0A%23ChrootDirectory%20none%0A%23VersionAddendum%20none%0A%0A%23%20no%20default%20banner%20path%0ABanner%20/etc/issue%0A%0A%23%20Accept%20locale-related%20environment%20variables%0AAcceptEnv%20LANG%20LC_CTYPE%20LC_NUMERIC%20LC_TIME%20LC_COLLATE%20LC_MONETARY%20LC_MESSAGES%0AAcceptEnv%20LC_PAPER%20LC_NAME%20LC_ADDRESS%20LC_TELEPHONE%20LC_MEASUREMENT%0AAcceptEnv%20LC_IDENTIFICATION%20LC_ALL%20LANGUAGE%0AAcceptEnv%20XMODIFIERS%0A%0A%23%20override%20default%20of%20no%20subsystems%0ASubsystem%09sftp%09/usr/libexec/openssh/sftp-server%0A%0A%23%20Example%20of%20overriding%20settings%20on%20a%20per-user%20basis%0A%23Match%20User%20anoncvs%0A%23%09X11Forwarding%20no%0A%23%09AllowTcpForwarding%20no%0A%23%09PermitTTY%20no%0A%23%09ForceCommand%20cvs%20server%0A%0A%23Log%20user%20connections%0ALogLevel%20VERBOSE%0A%0AUsePrivilegeSeparation%20sandbox
        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config

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

References:  11, 3, 9, BAI10.01, BAI10.02, BAI10.03, BAI10.05, 3.1.12, CCI-000318, CCI-000368, 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-7(a), CM-7(b), CM-6(a), AC-17(a), PR.IP-1, FIA_AFL.1, SRG-OS-000364-GPOS-00151, SRG-OS-000480-VMM-002000

Remediation Shell script:   (show)

Complexity:low
Disruption:low
Strategy:restrict
if [ -e "/etc/ssh/sshd_config" ] ; then
    LC_ALL=C sed -i "/^\s*GSSAPIAuthentication\s\+/Id" "/etc/ssh/sshd_config"
else
    touch "/etc/ssh/sshd_config"
fi
cp "/etc/ssh/sshd_config" "/etc/ssh/sshd_config.bak"
# Insert before the line matching the regex '^Match'.
line_number="$(LC_ALL=C grep -n "^Match" "/etc/ssh/sshd_config.bak" | LC_ALL=C sed 's/:.*//g')"
if [ -z "$line_number" ]; then
    # There was no match of '^Match', insert at
    # the end of the file.
    printf '%s\n' "GSSAPIAuthentication no" >> "/etc/ssh/sshd_config"
else
    head -n "$(( line_number - 1 ))" "/etc/ssh/sshd_config.bak" > "/etc/ssh/sshd_config"
    printf '%s\n' "GSSAPIAuthentication no" >> "/etc/ssh/sshd_config"
    tail -n "+$(( line_number ))" "/etc/ssh/sshd_config.bak" >> "/etc/ssh/sshd_config"
fi
# Clean up after ourselves.
rm "/etc/ssh/sshd_config.bak"
Remediation Ansible snippet:   (show)

Complexity:low
Disruption:low
Strategy:restrict
- name: Disable GSSAPI Authentication
  block:

    - name: Deduplicate values from /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: false
        regexp: (?i)^\s*GSSAPIAuthentication\s+
        state: absent

    - name: Insert correct line to /etc/ssh/sshd_config
      lineinfile:
        path: /etc/ssh/sshd_config
        create: true
        line: GSSAPIAuthentication no
        state: present
        insertbefore: ^[#\s]*Match
        validate: /usr/sbin/sshd -t -f %s
  when: ansible_virtualization_role != "guest" or ansible_virtualization_type != "docker"
  tags:
    - sshd_disable_gssapi_auth
    - medium_severity
    - restrict_strategy
    - low_complexity
    - low_disruption
    - no_reboot_needed
    - NIST-800-171-3.1.12
    - NIST-800-53-CM-7(a)
    - NIST-800-53-CM-7(b)
    - NIST-800-53-CM-6(a)
    - NIST-800-53-AC-17(a)
Remediation script:   (show)

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
      - contents:
          source: 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        filesystem: root
        mode: 0600
        path: /etc/ssh/sshd_config
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