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RHEL-07-010199 - The Red Hat Enterprise Linux operating system must be configured to prevent overwriting of custom authentication configuration settings by the authconfig utility - system-auth

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Information

When using the authconfig utility to modify authentication configuration settings, the 'system-auth' and 'password-auth' files and any custom settings that they may contain are overwritten. This can be avoided by creating new local configuration files and creating new or moving existing symbolic links to them. The authconfig utility will recognize the local configuration files and not overwrite them, while writing its own settings to the original configuration files.

Solution

Create custom configuration files and their corresponding symbolic links:

 Rename the existing configuration files (skip this step if symbolic links are already present):
 $ sudo mv /etc/pam.d/system-auth /etc/pam.d/system-auth-ac
 $ sudo mv /etc/pam.d/password-auth /etc/pam.d/password-auth-ac

 Create custom system-auth configuration file:
 $ sudo vi /etc/pam.d/system-auth-local

 The new file, at minimum, must contain the following lines:

 auth required pam_faillock.so preauth silent audit deny=3 even_deny_root fail_interval=900 unlock_time=900
 auth include system-auth-ac
 auth sufficient pam_unix.so try_first_pass
 auth [default=die] pam_faillock.so authfail audit deny=3 even_deny_root fail_interval=900 unlock_time=900

 account required pam_faillock.so
 account include system-auth-ac

 password requisite pam_pwhistory.so use_authtok remember=5 retry=3
 password include system-auth-ac
 password sufficient pam_unix.so sha512 shadow try_first_pass use_authtok

 session include system-auth-ac

 Create custom password-auth configuration file:
 $ sudo vi /etc/pam.d/password-auth-local

 The new file, at minimum, must contain the following lines:

 auth required pam_faillock.so preauth silent audit deny=3 even_deny_root fail_interval=900 unlock_time=900
 auth include password-auth-ac
 auth sufficient pam_unix.so try_first_pass
 auth [default=die] pam_faillock.so authfail audit deny=3 even_deny_root fail_interval=900 unlock_time=900

 account required pam_faillock.so
 account include password-auth-ac

 password requisite pam_pwhistory.so use_authtok remember=5 retry=3
 password include password-auth-ac
 password sufficient pam_unix.so sha512 shadow try_first_pass use_authtok

 session include password-auth-ac

 Create new or move existing symbolic links to the new custom configuration files:
 $ sudo ln -sf /etc/pam.d/system-auth-local /etc/pam.d/system-auth
 $ sudo ln -sf /etc/pam.d/password-auth-local /etc/pam.d/password-auth

 Once finished you should have the following file structure:
 $ sudo ls -1 /etc/pam.d/{password,system}-auth*

 /etc/pam.d/password-auth
 /etc/pam.d/password-auth-ac
 /etc/pam.d/password-auth-local
 /etc/pam.d/system-auth
 /etc/pam.d/system-auth-ac
 /etc/pam.d/system-auth-local

 Done.

 Note: With this solution in place any custom settings to 'system-auth' and 'password-auth' will be retained and not overwritten by the use of the authconfig utility. The authconfig utility will write its settings to 'system-auth-ac' and 'password-auth-ac' and continue to function as expected.

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_RHEL_7_V3R10_STIG.zip

Item Details

References: CAT|II, CCI|CCI-000196, Rule-ID|SV-255928r880830_rule, STIG-ID|RHEL-07-010199, Vuln-ID|V-255928

Plugin: Unix

Control ID: e8bc60f6b5f923fd4d9e30629e31888d2e72b959eb1eb24555e64af88aeac2d0