1.4.3 Ensure authentication required for single user mode - rescue

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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 /usr/lib/systemd/system/emergency.service and set ExecStart to use '/usr/sbin/sulogin':

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

Additional Information:

The systemctl option --fail is synonymous with --job-mode=fail. Using either is acceptable.

See Also

https://workbench.cisecurity.org/files/3288