Configure auditd to use audispd's syslog plugin

Description

To configure the auditd service to use the syslog plug-in of the audispd audit event multiplexor, set the active line in /etc/audit/plugins.d/syslog.conf to yes. Restart the auditd service:

$ sudo service auditd restart

Rationale

The auditd service does not include the ability to send audit records to a centralized server for management directly. It does, however, include a plug-in for audit event multiplexor (audispd) to pass audit records to the local syslog server.

Remediation

Shell script

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

#!/bin/bash

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

var_syslog_active="yes"

AUDISP_SYSLOGCONFIG=/etc/audit/plugins.d/syslog.conf

# Test if the config_file is a symbolic link. If so, use --follow-symlinks with sed.
# Otherwise, regular sed command will do.
sed_command=('sed' '-i')
if test -L "$AUDISP_SYSLOGCONFIG"; then
    sed_command+=('--follow-symlinks')
fi

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^active")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$var_syslog_active"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^active\\>" "$AUDISP_SYSLOGCONFIG"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    "${sed_command[@]}" "s/^active\\>.*/$escaped_formatted_output/gi" "$AUDISP_SYSLOGCONFIG"
else
    # \n is precaution for case where file ends without trailing newline
    
    printf '%s\n' "$formatted_output" >> "$AUDISP_SYSLOGCONFIG"
fi

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

Ansible playbook

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

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CJIS-5.4.1.1
  - NIST-800-171-3.3.1
  - NIST-800-53-AU-4(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.3
  - auditd_audispd_syslog_plugin_activated
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: enable syslog plugin
  lineinfile:
    dest: /etc/audit/plugins.d/syslog.conf
    regexp: ^active
    line: active = yes
    create: true
  when:
  - '"audit" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - CJIS-5.4.1.1
  - NIST-800-171-3.3.1
  - NIST-800-53-AU-4(1)
  - NIST-800-53-CM-6(a)
  - PCI-DSS-Req-10.5.3
  - auditd_audispd_syslog_plugin_activated
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed