The root account must be the only account having unrestricted access to RHEL 9 system.

STIG ID: RHEL-09-411100  |  SRG: SRG-OS-000480-GPOS-00227 |  Severity: high |  CCI: CCI-000366 |  Vulnerability Id: V-258059

Vulnerability Discussion

An account has root authority if it has a user identifier (UID) of "0". Multiple accounts with a UID of "0" afford more opportunity for potential intruders to guess a password for a privileged account. Proper configuration of sudo is recommended to afford multiple system administrators access to root privileges in an accountable manner.

Check

Verify that only the "root" account has a UID "0" assignment with the following command:

$ awk -F: '$3 == 0 {print $1}' /etc/passwd

root

If any accounts other than "root" have a UID of "0", this is a finding.

Fix

Change the UID of any account on the system, other than root, that has a UID of "0".

If the account is associated with system commands or applications, the UID should be changed to one greater than "0" but less than "1000". Otherwise, assign a UID of greater than "1000" that has not already been assigned.