1.5.3 Ensure authentication required for single user mode - rescue

Information

Single user mode (rescue mode) is used for recovery when the system detects an issue during boot or by manual selection from the bootloader.

Rationale:

Requiring authentication in single user mode (rescue mode) prevents an unauthorized user from rebooting the system into single user to gain root privileges without credentials.

Solution

Edit /usr/lib/systemd/system/rescue.service and add/modify the following line:

ExecStart=-/bin/sh -c '/usr/sbin/sulogin; echo 'Starting default target'; /usr/bin/systemctl --job-mode=fail --no-block default'

Edit /usr/lib/systemd/system/emergency.service and add/modify the following line:

ExecStart=-/bin/sh -c '/usr/sbin/sulogin; echo 'Starting default target'; /usr/bin/systemctl --job-mode=fail --no-block default'

See Also

https://workbench.cisecurity.org/files/3675