Vulnerability Discussion

If modification of login 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 Amazon Linux 2023 is configured so that the audit system prevents unauthorized changes to login 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 Amazon Linux 2023 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

To load the rules to the kernel immediately, use the following command:

$ sudo augenrules --load