System Audit Logs Must Have Mode 0750 or Less Permissive

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Description

If log_group in /etc/audit/auditd.conf is set to a group other than the root group account, change the mode of the audit log files with the following command:

$ sudo chmod 0750 /var/log/audit

Otherwise, change the mode of the audit log files with the following command:

$ sudo chmod 0700 /var/log/audit

Rationale

If users can write to audit logs, audit trails can be modified or destroyed.

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 dpkg-query --show --showformat='${db:Status-Status}
' 'kernel' 2>/dev/null | grep -q installed && dpkg-query --show --showformat='${db:Status-Status}\n' 'auditd' 2>/dev/null | grep -q installed; then

if LC_ALL=C grep -iw ^log_file /etc/audit/auditd.conf; then
  DIR=$(awk -F "=" '/^log_file/ {print $2}' /etc/audit/auditd.conf | tr -d ' ' | rev | cut -d"/" -f2- | rev)
else
  DIR="/var/log/audit"
fi


if LC_ALL=C grep -m 1 -q ^log_group /etc/audit/auditd.conf; then
  GROUP=$(awk -F "=" '/log_group/ {print $2}' /etc/audit/auditd.conf | tr -d ' ')
  if ! [ "${GROUP}" == 'root' ] ; then
    chmod 0750 $DIR
  else
    chmod 0700 $DIR
  fi
else
  chmod 0700 $DIR
fi

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