cis-gcp-cos-1-3-1

name	cis-gcp-cos-1.3.1
description	Ensure authentication required for single user mode
category	cis-gcp-cos
version	1.2.0
author	cyberstrike-official
tags	["cis","gcp","container-optimized-os","secure-boot","authentication","single-user-mode"]
cis_id	1.3.1
cis_benchmark	CIS Google Container-Optimized OS Benchmark v1.2.0
tech_stack	["gcp","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.3.1 Ensure authentication required for single user mode (Automated)

Description

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.

Audit Procedure

Run the following commands and verify that /sbin/sulogin or /usr/sbin/sulogin is used as shown:

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

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

# grep /systemd-sulogin-shell /usr/lib/systemd/system/emergency.service

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

Expected Result

The output should show ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue for rescue.service and ExecStart=-/usr/lib/systemd/systemd-sulogin-shell emergency for emergency.service.

Remediation

Rootfs is read-only file system. Therefore, update to an OS image which requires single user mode authentication.

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	4.7 Manage Default Accounts on Enterprise Assets and Software	x	x	x
v7	5.1 Establish Secure Configurations	x	x	x

Profile

Level 1 - Server | Automated