Uninstall avahi Server Package

Description

If the system does not need to have an Avahi server which implements the DNS Service Discovery and Multicast DNS protocols, the avahi-autoipd and avahi packages can be uninstalled.

Rationale

Automatic discovery of network services is not normally required for system functionality. It is recommended to remove this package to reduce the potential attack surface.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# CAUTION: This remediation script will remove avahi-daemon
#	   from the system, and may remove any packages
#	   that depend on avahi-daemon. Execute this
#	   remediation AFTER testing on a non-production
#	   system!

DEBIAN_FRONTEND=noninteractive apt-get remove -y "avahi-daemon"

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Ensure avahi-daemon is removed
  package:
    name: avahi-daemon
    state: absent
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - package_avahi_removed