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1.4.1 Ensure bootloader password is set

Information

Setting the boot loader password will require that anyone rebooting the system must enter a password before being able to set command line boot parameters

Requiring a boot password upon execution of the boot loader will prevent an unauthorized user from entering boot parameters or changing the boot partition. This prevents users from weakening security (e.g. turning off SELinux at boot time).

Solution

For newer grub2 based systems (Release 7.2 and newer), create an encrypted password with grub2-setpassword :

# grub2-setpassword

Enter password: <password>
Confirm password: <password>

Run the following command to script the grub2 configuration:

#!/usr/bin/env bash

GFCU()
{
 grubfile=$(find /boot -type f \( -name 'grubenv' -o -name 'grub.conf' -o -name 'grub.cfg' \) -exec grep -Pl '^\h*(kernelopts=|linux|kernel)' {} \;)
 grubdir=$(dirname "$grubfile")
 grub2-mkconfig -o "$grubdir/grub.cfg"
}
GFCU

OR for older grub2 based systems, create an encrypted password with grub2-mkpasswd-pbkdf2 :

# grub2-mkpasswd-pbkdf2

Enter password: <password>
Reenter password: <password>

Your PBKDF2 is <encrypted-password>

Add the following into /etc/grub.d/01_users or a custom /etc/grub.d configuration file:

cat <<EOF
set superusers="<username>"
password_pbkdf2 <username> <encrypted-password>
EOF

Note:

 -

If placing the information in a custom file, do not include the "cat << EOF" and "EOF" lines as the content is automatically added from these files

 -

The superuser/user information and password should not be contained in the /etc/grub.d/00_header file. The information can be placed in any /etc/grub.d file as long as that file is incorporated into grub.cfg It is preferable to enter this data into a custom file, such as /etc/grub.d/40_custom so it is not overwritten should the Grub package be updated

Run the following command to script the grub2 configuration:

#!/usr/bin/env bash

GFCU()
{
 grubfile=$(find /boot -type f \( -name 'grubenv' -o -name 'grub.conf' -o -name 'grub.cfg' \) -exec grep -Pl '^\h*(kernelopts=|linux|kernel)' {} \;)
 grubdir=$(dirname "$grubfile")
 grub2-mkconfig -o "$grubdir/grub.cfg"
}
GFCU

Impact:

 - If password protection is enabled, only the designated superuser can edit a Grub 2 menu item by pressing "e" or access the GRUB 2 command line by pressing "c"
 - If GRUB 2 is set up to boot automatically to a password-protected menu entry the user has no option to back out of the password prompt to select another menu entry. Holding the SHIFT key will not display the menu in this case. The user must enter the correct username and password. If unable, the configuration files will have to be edited via the LiveCD or other means to fix the problem
 - You can add --unrestricted to the menu entries to allow the system to boot without entering a password. Password will still be required to edit menu items.

See Also

https://workbench.cisecurity.org/benchmarks/8415

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND SERVICES ACQUISITION

References: 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv7|5.1

Plugin: Unix

Control ID: 4e003506046f06269f74f5bfad8c65d5bf17abfbed93e2f74e6ecedc6f149223