RHEL 9 duplicate User IDs (UIDs) must not exist for interactive users.

STIG ID: RHEL-09-411030  |  SRG: SRG-OS-000104-GPOS-00051 | Severity: medium |  CCI: CCI-000135,CCI-000764,CCI-000804

Vulnerability Discussion

To ensure accountability and prevent unauthenticated access, interactive users must be identified and authenticated to prevent potential misuse and compromise of the system.

Satisfies: SRG-OS-000104-GPOS-00051, SRG-OS-000121-GPOS-00062, SRG-OS-000042-GPOS-00020

Check

Verify that RHEL 9 contains no duplicate UIDs for interactive users with the following command:

$ sudo awk -F ":" 'list[$3]++{print $1, $3}' /etc/passwd

If output is produced and the accounts listed are interactive user accounts, this is a finding.

Fix

Edit the file "/etc/passwd" and provide each interactive user account that has a duplicate UID with a unique UID.