cis-ubuntu2004-v300-1-6-1

name	cis-ubuntu2004-v300-1-6-1
description	Ensure /etc/motd is configured
category	cis-networking
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","banners","motd","warning"]
cis_id	1.6.1
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.6.1 Ensure /etc/motd is configured (Automated)

Profile

• Level 1 - Server
• Level 1 - Workstation

Description

The contents of the /etc/motd file are displayed to users after login and function as a message of the day for authenticated users.

Unix-based systems have typically displayed information about the OS release and patch level upon logging in to the system. This information can be useful to developers who are developing software for a particular OS platform. If mingetty(8) supports the following options, they display operating system information: \m - machine architecture \r - operating system release \s - operating system name \v - operating system version

Rationale

Warning messages inform users who are attempting to login to the system of their legal status regarding the system and must include the name of the organization that owns the system and any monitoring policies that are in place. Displaying OS and patch level information in login banners also has the side effect of providing detailed system information to attackers attempting to target specific exploits of a system. Authorized users can easily get this information by running the uname -a command once they have logged in.

Audit Procedure

Command Line

Run the following script to verify MOTD files do not contain system information:

#!/usr/bin/env bash

{
   l_output="" l_output2=""
   a_files=()
   for l_file in /etc/motd{,.d/*}; do
      if grep -Psqi -- "(\\\v|\\\r|\\\m|\\\s|\b$(grep ^ID= /etc/os-release | cut -d= -f2 | sed -e 's/"//g')\b)" "$l_file"; then
            l_output2="$l_output2\n - File: \"$l_file\" includes system information"
      else
            a_files+=("$l_file")
      fi
   done
   if [ "${#a_files[@]}" -gt 0 ]; then
      echo -e "\n-  ** Please review the following files and verify their contents follow  site policy **\n- ** No MOTD files with any size were found. Please verify this conforms to  site policy **- - No MOTD files include system information\n- Audit Result:\n  ** PASS **\n\n\n- Audit Result:\n  ** FAIL **\n - Reason(s)  audit failure:\n\n