Ensure authentication required for single user mode

MediumLevel 1Automatedlinux

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.

How it is checked

Audit method: Shell command

shell

alt0() { command -v grep >/dev/null 2>&1 || { echo "step1: grep not installed"; return 1; }; o=$(bash -c 'grep /sbin/sulogin /usr/lib/systemd/system/rescue.service' 2>&1); printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'ExecStart=-/bin/sh -c "/sbin/sulogin; /usr/bin/systemctl --fail --no-block' || { echo step1: missing 'ExecStart=-/bin/sh -c "/sbin/sulogin; /usr/bin/systemctl --f'; return 1; }; printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'default"' || { echo step1: missing 'default"'; return 1; }; command -v grep >/dev/null 2>&1 || { echo "step2: grep not installed"; return 1; }; o=$(bash -c 'grep /sbin/sulogin /usr/lib/systemd/system/emergency.service' 2>&1); printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'ExecStart=-/bin/sh -c "/sbin/sulogin; /usr/bin/systemctl --fail --no-block' || { echo step2: missing 'ExecStart=-/bin/sh -c "/sbin/sulogin; /usr/bin/systemctl --f'; return 1; }; printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'default"' || { echo step2: missing 'default"'; return 1; }; }; if alt0; then echo compliant; fi

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Edit /usr/lib/systemd/system/rescue.service and /usr/lib/systemd/system/emergency.service and set ExecStart to use /sbin/sulogin or /usr/sbin/sulogin: ExecStart=-/bin/sh -c "/sbin/sulogin; /usr/bin/systemctl --fail --no-block default"

Properties

Operating systems: alinux-2
Tags: cis-convertedlinux
Reference: CIS Aliyun Linux 2 Benchmark v1.0.0 ARCHIVE - 1.4.2

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target linux