Configure auditd space_left Action on Low Disk Space

An XCCDF Rule

Description

The auditd service can be configured to take an action when disk space starts to run low. Edit the file /etc/audit/auditd.conf. Modify the following line, substituting ACTION appropriately:

space_left_action = ACTION

Possible values for ACTION are described in the auditd.conf man page. These include:

syslog
email
exec
suspend
single
halt

Set this to email (instead of the default, which is suspend) as it is more likely to get prompt attention. Acceptable values also include suspend, single, and halt.

Rationale

Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption.

ID: xccdf_org.ssgproject.content_rule_auditd_data_retention_space_left_action
Severity: Medium
References: 1 11 12 13 14 15 16 19 2 3 4 5 6 7 8

5.4.1.1

APO11.04 APO12.06 APO13.01 BAI03.05 BAI04.04 BAI08.02 DSS02.02 DSS02.04 DSS02.07 DSS03.01 DSS05.04 DSS05.07 MEA02.01

3.3.1

CCI-001855

164.312(a)(2)(ii)

4.2.3.10 4.3.3.3.9 4.3.3.5.8 4.3.4.4.7 4.3.4.5.6 4.3.4.5.7 4.3.4.5.8 4.4.2.1 4.4.2.2 4.4.2.4

SR 2.10 SR 2.11 SR 2.12 SR 2.8 SR 2.9 SR 6.1 SR 7.1 SR 7.2

A.12.1.3 A.12.4.1 A.12.4.2 A.12.4.3 A.12.4.4 A.12.7.1 A.16.1.4 A.16.1.5 A.16.1.7 A.17.2.1

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

DE.AE-3 DE.AE-5 PR.DS-4 PR.PT-1 RS.AN-1 RS.AN-4

Req-10.7

10.5.1

SRG-OS-000343-GPOS-00134
Updated: about 1 year ago

# Remediation is applicable only in certain platforms
if [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && dpkg-query --show --showformat='${db:Status-Status}\n' 'auditd' 2>/dev/null | grep -q installed; then

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

var_auditd_space_left_action="$(echo $var_auditd_space_left_action | cut -d \| -f 1)"
#
# If space_left_action present in /etc/audit/auditd.conf, change value
# to var_auditd_space_left_action, else
# add "space_left_action = $var_auditd_space_left_action" to /etc/audit/auditd.conf
#

AUDITCONFIG=/etc/audit/auditd.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' <<< "^space_left_action")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "$var_auditd_space_left_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 "^space_left_action\\>" "$AUDITCONFIG"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^space_left_action\\>.*/$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

Configure auditd space_left Action on Low Disk Space

Description

Rationale

Remediation - Shell Script