Cis Ubuntu2004 V300 6 3 4 3

6.3.4.3 Ensure audit log files group owner is configured (Automated)

Profile Applicability

• Level 2 - Server
• Level 2 - Workstation

Description

Audit log files contain information about the system and system activity.

Rationale

Access to audit records can reveal system and configuration data to attackers, potentially compromising its confidentiality.

Audit

Run the following command to verify log_group parameter is set to either adm or root in /etc/audit/auditd.conf:

grep -Piws -- '^\h*log_group\h*=\h*\h*(adm|root)\h*$' /etc/audit/auditd.conf | grep -Pvl -- '(adm)'

Nothing should be returned.

Using the path of the directory containing the audit logs, verify audit log files are owned by the "root" or "adm" group by running the following script:

#!/usr/bin/env bash
{
  if [ -e /etc/audit/auditd.conf ]; then
    l_fpath="$(dirname "$(awk -F= '/^\s*log_file/ {print $2}' /etc/audit/auditd.conf | xargs)")"
    [ find -L "$l_fpath" -not -path "$l_fpath"/lost+found -type f \( ! -group root -a ! -group adm \) -exec ls
  fi
}

Nothing should be returned.

Remediation

Run the following command to configure the audit log files to be group owned by adm:

[ find -L "$(dirname "$(awk -F= '/^\s*log_file/ {print $2}' /etc/audit/auditd.conf | xargs)")" -type f \( ! -group adm -a ! -group root \) -exec chgrp adm {} +

Run the following command to set the log_group parameter in the audit configuration file to log_group = adm:

[ sed -ri 's/^\s*#?\s*log_group\s*=\s*\S+(\s*.*)?$/log_group = adm\1/' /etc/audit/auditd.conf

Run the following command to restart the audit daemon to reload the configuration file:

systemctl restart auditd

References

1. NIST SP 800-53 Rev. 5: AU-3

CIS Controls

• v8: 3.3 Configure Data Access Control Lists
• v7: 14.6 Protect Information through Access Control Lists

MITRE ATT&CK Mappings

• Techniques: T1070, T1070.002, T1083, T1083.000
• Tactics: TA0007
• Mitigations: M1022