Vulnerability Discussion

Audit records provide a means to investigate events related to a security incident. Insufficient audit coverage will make identifying those responsible challenging or impossible.

This auditd policy will watch for and alert the system administrators regarding any modifications to the "/etc/passwd" file such as adding/removing/disabling users.

Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221, SRG-OS-000274-GPOS-00104, SRG-OS-000275-GPOS-00105, SRG-OS-000276-GPOS-00106, SRG-OS-000277-GPOS-00107

Check

Verify AlmaLinux OS 9 generates audit records for all account creations, modifications, disabling, and termination events that affect the "/etc/passwd" file, with the following command:

$ grep /etc/passwd /etc/audit/audit.rules

-w /etc/passwd -p wa -k identity

If the command does not return a line or the line is commented out, this is a finding.

Note: The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure AlmaLinux OS 9 to generate audit records for all account creations, modifications, disabling, and termination events that affect "/etc/passwd".

Add the following to the "/etc/audit/rules.d/audit.rules" file:

-w /etc/passwd -p wa -k identity

Merge the rules into /etc/audit/audit.rules:

$ augenrules --load

Reboot the server so the changes to take effect.