RHEL 9 must require a unique superusers name upon booting into single-user and maintenance modes.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-257789 | RHEL-09-212020 | SV-257789r1137691_rule | CCI-000213 | high |
| Description | ||||
| Having a nondefault grub superuser username makes password-guessing attacks less effective. | ||||
| STIG | Date | |||
| Red Hat Enterprise Linux 9 Security Technical Implementation Guide | 2026-02-05 | |||
Details
Check Text (C-257789r1137691_chk)
Verify the RHEL 9 boot loader superuser account has been set with the following command:
$ sudo grep -A1 "superusers" /etc/grub2.cfg
set superusers="<accountname>"
export superusers
password_pbkdf2 <accountname> ${GRUB2_PASSWORD}
Verify <accountname> is not a common name such as root, admin, or administrator.
If superusers contains easily guessable usernames, this is a finding.
Fix Text (F-61454r1134894_fix)
Configure RHEL 9 to have a unique username for the grub superuser account.
Edit the "/etc/grub.d/01_users" file and add or modify the following lines with a nondefault username for the superuser account:
set superusers="<accountname>"
export superusers
Once the superuser account has been added, update the grub.cfg file by running:
In RHEL 9.0, 9.1 and 9.2:
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
In RHEL 9.3 and later:
sudo grub2-mkconfig -o /boot/grub2/grub.cfg --update-bls-cmdline