Configure audispd's Plugin disk_full_action When Disk Is Full

An XCCDF Rule

Description

Configure the action the operating system takes if the disk the audit records are written to becomes full. Edit the file /etc/audit/audisp-remote.conf. Add or modify the following line, substituting ACTION appropriately:

disk_full_action = ACTION

Set this value to single to cause the system to switch to single user mode for corrective action. Acceptable values also include syslog and halt. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined.

Rationale

Taking appropriate action in case of a filled audit storage volume will minimize the possibility of losing audit records.

ID: xccdf_org.ssgproject.content_rule_auditd_audispd_disk_full_action
Severity: Medium
References: CCI-001851

AU-5(1) AU-5(2) AU-5(4) AU-5(b) CM-6(a)

SRG-OS-000342-GPOS-00133 SRG-OS-000479-GPOS-00224
Updated: about 1 year ago

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

var_audispd_disk_full_action='<xccdf-1.2:sub xmlns:xccdf-1.2="http://checklists.nist.gov/xccdf/1.2" idref="xccdf_org.ssgproject.content_value_var_audispd_disk_full_action" use="legacy"/>'

AUDITCONFIG=/etc/audit/audisp-remote.conf

# 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' <<< "^disk_full_action")

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

# 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 "^disk_full_action\\>" "$AUDITCONFIG"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^disk_full_action\\>.*/$escaped_formatted_output/gi" "$AUDITCONFIG"
else
    if [[ -s "$AUDITCONFIG" ]] && [[ -n "$(tail -c 1 -- "$AUDITCONFIG" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "$AUDITCONFIG"
    fi
    printf '%s\n' "$formatted_output" >> "$AUDITCONFIG"
fi

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

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-AU-5(1)
  - NIST-800-53-AU-5(2)  - NIST-800-53-AU-5(4)
  - NIST-800-53-AU-5(b)
  - NIST-800-53-CM-6(a)
  - auditd_audispd_disk_full_action
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
- name: XCCDF Value var_audispd_disk_full_action # promote to variable
  set_fact:
    var_audispd_disk_full_action: !!str <xccdf-1.2:sub xmlns:xccdf-1.2="http://checklists.nist.gov/xccdf/1.2" idref="xccdf_org.ssgproject.content_value_var_audispd_disk_full_action" use="legacy"/>
  tags:
    - always

- name: Make sure that disk full action is configured for Audispd
  lineinfile:
    path: /etc/audit/audisp-remote.conf
    line: disk_full_action = {{ var_audispd_disk_full_action }}
    regexp: ^\s*disk_full_action\s*=.*$
    create: true
    state: present
  when:
  - '"audit" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-53-AU-5(1)
  - NIST-800-53-AU-5(2)
  - NIST-800-53-AU-5(4)
  - NIST-800-53-AU-5(b)
  - NIST-800-53-CM-6(a)
  - auditd_audispd_disk_full_action
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

Configure audispd's Plugin disk_full_action When Disk Is Full

Description

Rationale

Remediation - Shell Script

Remediation - Ansible