Vulnerability Discussion
If modification of login user identifiers (UIDs) is not prevented, they can be changed by nonprivileged users and make auditing complicated or impossible.
Satisfies: SRG-OS-000462-GPOS-00206, SRG-OS-000475-GPOS-00220, SRG-OS-000057-GPOS-00027, SRG-OS-000058-GPOS-00028, SRG-OS-000059-GPOS-00029
Check
Verify the audit system prevents unauthorized changes to logon UIDs with the following command:
$ sudo grep -i immutable /etc/audit/audit.rules
--loginuid-immutable
If the "--loginuid-immutable" option is not returned in the "/etc/audit/audit.rules", or the line is commented out, this is a finding.
Fix
Configure RHEL 9 auditing to prevent modification of login UIDs once they are set by adding the following line to /etc/audit/rules.d/audit.rules:
--loginuid-immutable
The audit daemon must be restarted for the changes to take effect.