TOSS 5 must require a unique superuser name upon booting into single-user and maintenance modes.

Having a nondefault grub superuser username makes password-guessing attacks less effective.

Verify the boot loader superuser account has been set using the following command:

$ sudo grep -A1 "superusers" /etc/grub2.cfg 

set superusers="<superusers-account>" export superusers

The <superusers-account> is the actual account name, which is different from common names like "root", "admin", or "administrator".

If superusers contains easily guessable usernames, this is a finding.

Configure TOSS 5 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 in the "### BEGIN /etc/grub.d/01_users ###" section:

set superusers="superusers-account" export superusers

Once the superuser account has been added, update the grub.cfg file using the following command:

$ sudo grubby --update-kernel=ALL