InformationThe operating system must not allow removable media to be used as the boot loader unless approved.
Malicious users with removable boot media can gain access to a system configured to use removable media as the boot loader. If removable media is designed to be used as the boot loader, the requirement must be documented with the Information System Security Officer (ISSO).
SolutionRemove alternate methods of booting the system from removable media or document the configuration to boot from removable media with the Authorizing Official.
Example: vim /etc/default/grub
Add this in the first menu entry
Any changes made to /etc/default/grub require you to run grub2-mkconfig to re-generate the /boot/grub2/grub.cfg file.
# grub2-mkconfig -o /boot/grub2/grub.cfg
Category: CONFIGURATION MANAGEMENT
References: 800-53|CM-3f., 800-53|CM-5(1), 800-53|CM-6c., 800-53|CM-11(2), CCI|CCI-000318, CCI|CCI-000368, CCI|CCI-001812, CCI|CCI-001813, CCI|CCI-001814, CSCv7|5.1, Rule-ID|SV-204501r603261_rule, STIG-ID|RHEL-07-021700
Control ID: 484c5e5e46c8f2aeee1e297aa85504d3e0110cb67fcdd516d71a0369441701aa