cis-ubuntu1804-v220-5-2-3-5

name	cis-ubuntu1804-v220-5-2-3-5
version	2.2.0
date_published	"2024-01-01T00:00:00.000Z"
category	cis-logging
description	Ensure events that modify the system's network environment are collected
author	CIS Benchmarks
tags	["cis","ubuntu","linux","ubuntu-18.04","auditing","auditd"]
target	{"platform":"linux","version":"18.04"}
severity_boost	{}

5.2.3.5 Ensure events that modify the system's network environment are collected

Profile Applicability

• Level 2 - Server
• Level 2 - Workstation

Description

Record changes to network environment files or system calls. The below parameters monitors the following system calls, and write an audit event on system call exit:

• sethostname - set the systems host name
• setdomainname - set the systems domain name

The files being monitored are:

• /etc/issue and /etc/issue.net - messages displayed pre-login
• /etc/hosts - file containing host names and associated IP addresses
• /etc/networks - symbolic names for networks
• /etc/network/ - directory containing network interface scripts and configurations files

Rationale

Monitoring sethostname and setdomainname will identify potential unauthorized changes to host and domainname of a system. The changing of these names could potentially break security parameters that are set based on those names. The /etc/hosts file is monitored for changes that can indicate an unauthorized intruder is trying to change machine associations with IP addresses and trick users and processes into connecting to unintended machines. Monitoring /etc/issue and /etc/issue.net is important, as intruders could put disinformation into those files and trick users into providing information to the intruder. Monitoring /etc/network is important as it can show if network interfaces or scripts are being modified in a way that can lead to the machine becoming unavailable or compromised. All audit records should have a relevant tag associated with them.

Audit

64 Bit systems

On disk configuration

Run the following commands to check the on disk rules:

awk '/^ *-a *always,exit/ \
&&/ -F *arch=b(32|64)/ \
&&/ -S/ \
&&(/sethostname/ \
 ||/setdomainname/) \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)/' /etc/audit/rules.d/*.rules

awk '/^ *-w/ \
&&(/\/etc\/issue/ \
 ||/\/etc\/issue.net/ \
 ||/\/etc\/hosts/ \
 ||/\/etc\/networks/ \
 ||/\/etc\/network\/ /) \
&&/ +-p *wa/ \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)/' /etc/audit/rules.d/*.rules

Verify the output matches:

-a always,exit -F arch=b64 -S sethostname,setdomainname -k system-locale
-a always,exit -F arch=b32 -S sethostname,setdomainname -k system-locale
-w /etc/issue -p wa -k system-locale
-w /etc/issue.net -p wa -k system-locale
-w /etc/hosts -p wa -k system-locale
-w /etc/networks -p wa -k system-locale
-w /etc/network/ -p wa -k system-locale