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documentation_complete: true
title: 'Set the UEFI Boot Loader Admin Username to a Non-Default Value'
description: |-
The grub2 boot loader should have a superuser account and password
protection enabled to protect boot-time settings.
<br /><br />
To maximize the protection, select a password-protected superuser account with unique name, and modify the
<tt>/etc/grub.d/01_users</tt> configuration file to reflect the account name change.
<br /><br />
It is highly suggested not to use common administrator account names like root,
admin, or administrator for the grub2 superuser account.
<br /><br />
Change the superuser to a different username (The default is 'root').
<pre>$ sed -i 's/\(set superusers=\).*/\1"<unique user ID>"/g' /etc/grub.d/01_users</pre>
The line mentioned above must be followed by the line
<pre>export superusers</pre>
so that the <tt>superusers</tt> is honored.
<br /><br />
Once the superuser account has been added,
update the
<tt>grub.cfg</tt> file by running:
{{%- if "rhel" in product %}}
<pre>grub2-mkconfig -o /boot/grub2/grub.cfg</pre>
{{%- else %}}
<pre>{{{ grub_command("update") }}}</pre>
{{%- endif %}}
rationale: |-
Having a non-default grub superuser username makes password-guessing attacks less effective.
severity: medium
identifiers:
cce@rhcos4: CCE-83540-5
cce@rhel8: CCE-83542-1
cce@rhel9: CCE-89427-9
cce@rhel10: CCE-89685-2
references:
cis-csc: 11,12,14,15,16,18,3,5
cobit5: DSS05.02,DSS05.04,DSS05.05,DSS05.07,DSS06.03,DSS06.06
cui: 3.4.5
hipaa: 164.308(a)(1)(ii)(B),164.308(a)(7)(i),164.308(a)(7)(ii)(A),164.310(a)(1),164.310(a)(2)(i),164.310(a)(2)(ii),164.310(a)(2)(iii),164.310(b),164.310(c),164.310(d)(1),164.310(d)(2)(iii)
isa-62443-2009: 4.3.3.2.2,4.3.3.5.1,4.3.3.5.2,4.3.3.5.3,4.3.3.5.4,4.3.3.5.5,4.3.3.5.6,4.3.3.5.7,4.3.3.5.8,4.3.3.6.1,4.3.3.6.2,4.3.3.6.3,4.3.3.6.4,4.3.3.6.5,4.3.3.6.6,4.3.3.6.7,4.3.3.6.8,4.3.3.6.9,4.3.3.7.1,4.3.3.7.2,4.3.3.7.3,4.3.3.7.4
isa-62443-2013: 'SR 1.1,SR 1.10,SR 1.11,SR 1.12,SR 1.13,SR 1.2,SR 1.3,SR 1.4,SR 1.5,SR 1.6,SR 1.7,SR 1.8,SR 1.9,SR 2.1,SR 2.2,SR 2.3,SR 2.4,SR 2.5,SR 2.6,SR 2.7'
iso27001-2013: A.6.1.2,A.7.1.1,A.9.1.2,A.9.2.1,A.9.2.3,A.9.4.1,A.9.4.4,A.9.4.5
nist: CM-6(a)
nist-csf: PR.AC-4,PR.AC-6,PR.PT-3
srg: SRG-OS-000080-GPOS-00048
stigid@ol7: OL07-00-010492
stigid@ol8: OL08-00-010141
ocil_clause: 'superuser account is not set or is set to an existing name or to a common name'
ocil: |-
To verify the boot loader superuser account has been set, run the following
command:
<pre>sudo grep -A1 "superusers" {{{ grub2_uefi_boot_path }}}/grub.cfg</pre>
The output should show the following:
<pre>set superusers="<b>superusers-account</b>"
export superusers</pre>
where superusers-account is the actual account name different from common names like root,
admin, or administrator and different from any other existing user name.
warnings:
- general: |-
To prevent hard-coded admin usernames, automatic remediation of this control is not available. Remediation
must be automated as a component of machine provisioning, or followed manually as outlined above.
Also, do NOT manually add the superuser account and password to the
<tt>grub.cfg</tt> file as the grub2-mkconfig command overwrites this file.
fixtext: |-
Configure {{{ full_name }}} to have a unique username for the grub superuser account.
Select a password-protected superuser account with unique name, and modify the
"/etc/grub.d/01_users" configuration file to reflect the account name change.
Add or edit the following line in /etc/grub.d/01_users:
set superusers="superusers-account"
export superusers
Once the superuser account has been added, update the grub.cfg file by running:
{{%- if "rhel" in product %}}
<pre>grub2-mkconfig -o /boot/grub2/grub.cfg</pre>
{{%- else %}}
<pre>{{{ grub_command("update") }}}</pre>
{{%- endif %}}
srg_requirement: '{{{ full_name }}} systems booted with United Extensible Firmware Interface (UEFI) must require a unique superusers name upon booting into single-user mode and maintenance.'
|
