Disable Avahi Server Software

An XCCDF Rule

Description

The avahi-daemon service can be disabled with the following command:

$ sudo systemctl mask --now avahi-daemon.service

Rationale

Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Its functionality is convenient but is only appropriate if the local network can be trusted.

ID: xccdf_org.ssgproject.content_rule_service_avahi-daemon_disabled
Severity: Medium
References: 11 14 3 9

BAI10.01 BAI10.02 BAI10.03 BAI10.05 DSS05.02 DSS05.05 DSS06.06

CCI-000366

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 4.3.4.3.2 4.3.4.3.3

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 SR 7.6

A.12.1.2 A.12.5.1 A.12.6.2 A.14.2.2 A.14.2.3 A.14.2.4 A.9.1.2

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

PR.IP-1 PR.PT-3

2.2.4
Updated: about 1 year ago


[customizations.services]
disabled = ["avahi-daemon"]

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)  - NIST-800-53-CM-7(b)
  - PCI-DSSv4-2.2.4
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_avahi-daemon_disabled

- name: Block Disable service avahi-daemon
  block:

  - name: Disable service avahi-daemon
    block:

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

    - name: Intentionally ignored previous 'Disable service avahi-daemon' failure,
        service was already disabled
      meta: noop
  when: ( ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman",
    "container"] and "avahi" in ansible_facts.packages )
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSSv4-2.2.4
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_avahi-daemon_disabled

- name: Unit Socket Exists - avahi-daemon.socket
  command: systemctl -q list-unit-files avahi-daemon.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 "avahi" in ansible_facts.packages )
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSSv4-2.2.4
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_avahi-daemon_disabled

- name: Disable socket avahi-daemon
  systemd:
    name: avahi-daemon.socket
    enabled: 'no'
    state: stopped
    masked: 'yes'
  when:
  - ( ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
    and "avahi" in ansible_facts.packages )
  - socket_file_exists.stdout_lines is search("avahi-daemon.socket",multiline=True)
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSSv4-2.2.4
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_avahi-daemon_disabled

include disable_avahi-daemon

class disable_avahi-daemon {
  service {'avahi-daemon':
    enable => false,
    ensure => 'stopped',  }
}

# Remediation is applicable only in certain platforms
if ( [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && rpm --quiet -q avahi ); then

SYSTEMCTL_EXEC='/usr/bin/systemctl'
"$SYSTEMCTL_EXEC" stop 'avahi-daemon.service'
"$SYSTEMCTL_EXEC" disable 'avahi-daemon.service'"$SYSTEMCTL_EXEC" mask 'avahi-daemon.service'
# Disable socket activation if we have a unit file for it
if "$SYSTEMCTL_EXEC" -q list-unit-files avahi-daemon.socket; then
    "$SYSTEMCTL_EXEC" stop 'avahi-daemon.socket'
    "$SYSTEMCTL_EXEC" mask 'avahi-daemon.socket'
fi
# The service may not be running because it has been started and failed,
# so let's reset the state so OVAL checks pass.
# Service should be 'inactive', not 'failed' after reboot though.
"$SYSTEMCTL_EXEC" reset-failed 'avahi-daemon.service' || true

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

Disable Avahi Server Software

Description

Rationale

Remediation - OS Build Blueprint

Remediation - Ansible

Remediation - Puppet

Remediation - Shell Script