Cis Ubuntu2004 V300 6 3 4 4

6.3.4.4 Ensure the audit log file directory mode is configured (Automated)

Profile Applicability

• Level 2 - Server
• Level 2 - Workstation

Description

The audit log directory contains audit log files.

Rationale

Audit information includes all information including: audit records, audit settings and audit reports. This information is needed to successfully audit system activity. This information must be protected from unauthorized modification or deletion. If this information were to be compromised, forensic analysis and discovery of the true source of potentially malicious system activity is impossible to achieve.

Audit

Run the following script to verify the audit log directory is mode 0750 or more restrictive:

#!/usr/bin/env bash
{
  l_perm_mask="0027"
  if [ -e "/etc/audit/auditd.conf" ]; then
    l_audit_log_directory="$(dirname "$(awk -F= '/^\s*log_file/ {print $2}' /etc/audit/auditd.conf | xargs)")"
    if [ -d "$l_audit_log_directory" ]; then
      l_maxperm="$(printf '%o' $(( 0777 & ~$l_perm_mask )) )"
      l_directory_mode="$(stat -Lc '%#a' "$l_audit_log_directory")"
      if [ $(( $l_directory_mode & $l_perm_mask )) -gt 0 ]; then
        echo -e "\n- Audit Result:\n ** FAIL **\n - Directory: \"$l_audit_log_directory\" is mode: \"$l_directory_mode\"\n (should be mode: \"$l_maxperm\" or more restrictive)\n"
      else
        echo -e "\n- Audit Result:\n ** PASS **\n - Directory: \"$l_audit_log_directory\" is mode: \"$l_directory_mode\"\n (should be mode: \"$l_maxperm\" or more restrictive)\n"
      fi
    else
      echo -e "\n- Audit Result:\n ** FAIL **\n - Log file directory not set in \"/etc/audit/auditd.conf\" please set log file directory"
    fi
  else
    echo -e "\n- Audit Result:\n ** FAIL **\n - File: \"/etc/audit/auditd.conf\" not found\n - ** Verify auditd is installed **"
  fi
}

Remediation

Run the following command to configure the audit log directory to have a mode of "0750" or less permissive:

chmod g-w,o-rwx "$(dirname "$(awk -F= '/^\s*log_file/ {print $2}' /etc/audit/auditd.conf | xargs)")"

Default Value

750

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