Disable SSH Server If Possible

An XCCDF Rule

Description

The SSH server service, sshd, is commonly needed. However, if it can be disabled, do so. This is unusual, as SSH is a common method for encrypted and authenticated remote access.

ID: xccdf_org.ssgproject.content_rule_service_sshd_disabled
Severity: High
References: CM-3(6) IA-2(4)

SRG-APP-000141-CTR-000315 SRG-APP-000185-CTR-000490
Updated: over 1 year ago

Remediation Templates

include disable_sshd
class disable_sshd {
  service {'sshd':
    enable => false,
    ensure => 'stopped',
  }
}

[customizations.services]
masked = ["sshd"]

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-3(6)
  - NIST-800-53-IA-2(4)  - disable_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - service_sshd_disabled
- name: Disable SSH Server If Possible - Collect systemd Services Present in the System
  ansible.builtin.command: systemctl -q list-unit-files --type service
  register: service_exists
  changed_when: false
  failed_when: service_exists.rc not in [0, 1]
  check_mode: false
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-3(6)
  - NIST-800-53-IA-2(4)
  - disable_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - service_sshd_disabled

- name: Disable SSH Server If Possible - Ensure sshd.service is Masked
  ansible.builtin.systemd:
    name: sshd.service
    state: stopped
    enabled: false
    masked: true
  when:
  - '"kernel" in ansible_facts.packages'
  - service_exists.stdout_lines is search("sshd.service", multiline=True)
  tags:
  - NIST-800-53-CM-3(6)
  - NIST-800-53-IA-2(4)
  - disable_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - service_sshd_disabled

- name: Unit Socket Exists - sshd.socket
  ansible.builtin.command: systemctl -q list-unit-files sshd.socket
  register: socket_file_exists
  changed_when: false
  failed_when: socket_file_exists.rc not in [0, 1]
  check_mode: false
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-3(6)
  - NIST-800-53-IA-2(4)
  - disable_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - service_sshd_disabled

- name: Disable SSH Server If Possible - Disable Socket sshd
  ansible.builtin.systemd:
    name: sshd.socket
    enabled: false
    state: stopped
    masked: true
  when:
  - '"kernel" in ansible_facts.packages'
  - socket_file_exists.stdout_lines is search("sshd.socket", multiline=True)
  tags:
  - NIST-800-53-CM-3(6)
  - NIST-800-53-IA-2(4)
  - disable_strategy
  - high_severity
  - low_complexity
  - low_disruption
  - no_reboot_needed
  - service_sshd_disabled

Disable SSH Server If Possible

Description

Remediation Templates

A Puppet Snippet

OS Build Blueprint

An Ansible Snippet