Vulnerability Discussion

If the system does not require valid root authentication before it boots into emergency or rescue mode, anyone who invokes emergency or rescue mode is granted privileged access to all files on the system.

Check

Determine if the system requires authentication for rescue mode with the following command:

$ sudo grep sulogin-shell /usr/lib/systemd/system/rescue.service

ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue

If the "ExecStart" line is configured for anything other than "/usr/lib/systemd/systemd-sulogin-shell rescue" or is commented out or missing, this is a finding.

Fix

Configure the system to require authentication upon booting into rescue mode by adding the following line to the "/usr/lib/systemd/system/rescue.service" file:

ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue