Require Authentication for Single User Mode

An XCCDF Rule

Description

Single-user mode is intended as a system recovery method, providing a single user root access to the system by providing a boot option at startup.

By default, single-user mode is protected by requiring a password and is set in /usr/lib/systemd/system/rescue.service.

Rationale

This prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.

ID: xccdf_org.ssgproject.content_rule_require_singleuser_auth
Severity: Medium
References: 1 11 12 14 15 16 18 3 5

DSS05.02 DSS05.04 DSS05.05 DSS05.07 DSS05.10 DSS06.03 DSS06.06 DSS06.10

3.1.1 3.4.5

CCI-000213

164.308(a)(1)(ii)(B) 164.308(a)(7)(i) 164.308(a)(7)(ii)(A) 164.310(a)(1) 164.310(a)(2)(i) 164.310(a)(2)(ii) 164.310(a)(2)(iii) 164.310(b) 164.310(c) 164.310(d)(1) 164.310(d)(2)(iii)

4.3.3.2.2 4.3.3.5.1 4.3.3.5.2 4.3.3.5.3 4.3.3.5.4 4.3.3.5.5 4.3.3.5.6 4.3.3.5.7 4.3.3.5.8 4.3.3.6.1 4.3.3.6.2 4.3.3.6.3 4.3.3.6.4 4.3.3.6.5 4.3.3.6.6 4.3.3.6.7 4.3.3.6.8 4.3.3.6.9 4.3.3.7.1 4.3.3.7.2 4.3.3.7.3 4.3.3.7.4

SR 1.1 SR 1.10 SR 1.11 SR 1.12 SR 1.13 SR 1.2 SR 1.3 SR 1.4 SR 1.5 SR 1.6 SR 1.7 SR 1.8 SR 1.9 SR 2.1 SR 2.2 SR 2.3 SR 2.4 SR 2.5 SR 2.6 SR 2.7

0421 0422 0431 0974 1173 1401 1504 1505 1546 1557 1558 1559 1560 1561

A.18.1.4 A.6.1.2 A.7.1.1 A.9.1.2 A.9.2.1 A.9.2.2 A.9.2.3 A.9.2.4 A.9.2.6 A.9.3.1 A.9.4.1 A.9.4.2 A.9.4.3 A.9.4.4 A.9.4.5

CIP-003-8 R5.1.1 CIP-003-8 R5.3 CIP-004-6 R2.2.3 CIP-004-6 R2.3 CIP-007-3 R5.1 CIP-007-3 R5.1.2 CIP-007-3 R5.2 CIP-007-3 R5.3.1 CIP-007-3 R5.3.2 CIP-007-3 R5.3.3

AC-3 CM-6(a) IA-2

PR.AC-1 PR.AC-4 PR.AC-6 PR.AC-7 PR.PT-3

FIA_UAU.1

SRG-OS-000080-GPOS-00048
Updated: 5 days ago

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel; then

found=false

# set value in all files if they contain section or keyfor f in $(echo -n "/etc/systemd/system/rescue.service.d/10-oscap.conf"); do
    if [ ! -e "$f" ]; then
        continue
    fi

    # find key in section and change value
    if grep -qzosP "[[:space:]]*\[Service\]([^\n\[]*\n+)+?[[:space:]]*ExecStart" "$f"; then

            sed -i "s/ExecStart[^(\n)]*/ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue/" "$f"

            found=true

    # find section and add key = value to it
    elif grep -qs "[[:space:]]*\[Service\]" "$f"; then

            sed -i "/[[:space:]]*\[Service\]/a ExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue" "$f"

            found=true
    fi
done

# if section not in any file, append section with key = value to FIRST file in files parameter
if ! $found ; then
    file=$(echo "/etc/systemd/system/rescue.service.d/10-oscap.conf" | cut -f1 -d ' ')
    mkdir -p "$(dirname "$file")"

    echo -e "[Service]\nExecStart=-/usr/lib/systemd/systemd-sulogin-shell rescue" >> "$file"

fi

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.1
  - NIST-800-171-3.4.5  - NIST-800-53-AC-3
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-2
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - require_singleuser_auth
  - restrict_strategy

- name: Require Authentication for Single User Mode - Require emergency user mode
    password
  community.general.ini_file:
    path: /etc/systemd/system/rescue.service.d/10-oscap.conf
    section: Service
    option: ExecStart
    value: -/usr/lib/systemd/systemd-sulogin-shell rescue
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-171-3.1.1
  - NIST-800-171-3.4.5
  - NIST-800-53-AC-3
  - NIST-800-53-CM-6(a)
  - NIST-800-53-IA-2
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - require_singleuser_auth
  - restrict_strategy

Require Authentication for Single User Mode

Description

Rationale

Remediation - Shell Script

Remediation - Ansible