Disable the Automounter

An XCCDF Rule

Description

The autofs daemon mounts and unmounts filesystems, such as user home directories shared via NFS, on demand. In addition, autofs can be used to handle removable media, and the default configuration provides the cdrom device as /misc/cd. However, this method of providing access to removable media is not common, so autofs can almost always be disabled if NFS is not in use. Even if NFS is required, it may be possible to configure filesystem mounts statically by editing /etc/fstab rather than relying on the automounter.

The autofs service can be disabled with the following command:

$ sudo systemctl mask --now autofs.service

Rationale

Disabling the automounter permits the administrator to statically control filesystem mounting through /etc/fstab.

Additionally, automatically mounting filesystems permits easy introduction of unknown devices, thereby facilitating malicious activity.

ID: xccdf_org.ssgproject.content_rule_service_autofs_disabled
Severity: Medium
References: 1 12 15 16 5

APO13.01 DSS01.04 DSS05.03 DSS05.04 DSS05.05 DSS05.07 DSS05.10 DSS06.03 DSS06.10

3.4.6

CCI-000366 CCI-000778 CCI-001958

164.308(a)(3)(i) 164.308(a)(3)(ii)(A) 164.310(d)(1) 164.310(d)(2) 164.312(a)(1) 164.312(a)(2)(iv) 164.312(b)

4.3.3.2.2 4.3.3.5.1 4.3.3.5.2 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 4.3.3.7.2 4.3.3.7.4

SR 1.1 SR 1.10 SR 1.13 SR 1.2 SR 1.3 SR 1.4 SR 1.5 SR 1.7 SR 1.8 SR 1.9 SR 2.1 SR 2.6

A.11.2.6 A.13.1.1 A.13.2.1 A.18.1.4 A.6.2.1 A.6.2.2 A.7.1.1 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.9.4.2 A.9.4.3

CM-6(a) CM-7(a) CM-7(b) MP-7

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

SRG-OS-000114-GPOS-00059 SRG-OS-000378-GPOS-00163 SRG-OS-000480-GPOS-00227
Updated: about 1 year ago


[customizations.services]
disabled = ["autofs"]

include disable_autofs

class disable_autofs {
  service {'autofs':
    enable => false,
    ensure => 'stopped',  }
}

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-MP-7
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_autofs_disabled

- name: Block Disable service autofs
  block:

  - name: Disable service autofs
    block:

    - name: Disable service autofs
      systemd:
        name: autofs.service
        enabled: 'no'
        state: stopped
        masked: 'yes'
    rescue:

    - name: Intentionally ignored previous 'Disable service autofs' failure, service
        was already disabled
      meta: noop
  when: ( ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman",
    "container"] and "autofs" in ansible_facts.packages )
  tags:
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-MP-7
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_autofs_disabled

- name: Unit Socket Exists - autofs.socket
  command: systemctl -q list-unit-files autofs.socket
  register: socket_file_exists
  changed_when: false
  failed_when: socket_file_exists.rc not in [0, 1]
  check_mode: false
  when: ( ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman",
    "container"] and "autofs" in ansible_facts.packages )
  tags:
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-MP-7
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_autofs_disabled

- name: Disable socket autofs
  systemd:
    name: autofs.socket
    enabled: 'no'
    state: stopped
    masked: 'yes'
  when:
  - ( ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
    and "autofs" in ansible_facts.packages )
  - socket_file_exists.stdout_lines is search("autofs.socket",multiline=True)
  tags:
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - NIST-800-53-MP-7
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_autofs_disabled

Disable the Automounter

Description

Rationale

Remediation - OS Build Blueprint

Remediation - Puppet

Remediation - Ansible