Vulnerability Discussion

If the system does not require valid authentication before it boots into single-user or maintenance mode, anyone who invokes single-user or maintenance mode is granted privileged access to all files on the system. GRUB 2 is the default boot loader for RHEL 7 and is designed to require a password to boot into single-user mode or make modifications to the boot menu.

Check

For systems that use UEFI, this is Not Applicable.

For systems that are running a version of RHEL prior to 7.2, this is Not Applicable.

Verify that a unique name is set as the "superusers" account:

# grep -iw "superusers" /boot/grub2/grub.cfg
set superusers="[someuniquestringhere]"
export superusers

If "superusers" is not set to a unique name or is missing a name, this is a finding.

Fix

Configure the system to have a unique name for the grub superusers account.

Edit the /boot/grub2/grub.cfg file and add or modify the following lines in the "### BEGIN /etc/grub.d/01_users ###" section:

set superusers="[someuniquestringhere]"
export superusers
password_pbkdf2 [someuniquestringhere] ${GRUB2_PASSWORD}