cis-ubuntu1804-v220-5-2-3-4

name	cis-ubuntu1804-v220-5-2-3-4
version	2.2.0
date_published	"2024-01-01T00:00:00.000Z"
category	cis-logging
description	Ensure events that modify date and time information are collected
author	CIS Benchmarks
tags	["cis","ubuntu","linux","ubuntu-18.04","auditing","auditd"]
target	{"platform":"linux","version":"18.04"}
severity_boost	{}

5.2.3.4 Ensure events that modify date and time information are collected

Profile Applicability

• Level 2 - Server
• Level 2 - Workstation

Description

Capture events where the system date and/or time has been modified. The parameters in this section are set to determine if the:

• adjtimex - tune kernel clock
• settimeofday - set time using timeval and timezone structures
• stime - using seconds since 1/1/1970
• clock_settime - allows for the setting of several internal clocks and timers

system calls have been executed. Further, ensure to write an audit record to the configured audit log file upon exit, tagging the records with a unique identifier such as "time-change".

Rationale

Unexpected changes in system date and/or time could be a sign of malicious activity on the system.

Audit

64 Bit systems

On disk configuration

Run the following command to check the on disk rules:

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

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

Verify the output matches:

-a always,exit -F arch=b64 -S adjtimex,settimeofday,clock_settime -k time-change
-a always,exit -F arch=b32 -S adjtimex,settimeofday,clock_settime -k time-change
-w /etc/localtime -p wa -k time-change

Running configuration

Run the following command to check loaded rules:

auditctl -l | awk '/^ *-a *always,exit/ \
&&/ -F *arch=b(32|64)/ \
&&/ -S/ \
&&(/adjtimex/ \
 ||/settimeofday/ \
 ||/clock_settime/ ) \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)/'

auditctl -l | awk '/^ *-w/ \
&&/\/etc\/localtime/ \
&&/ +-p *wa/ \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)/'

Verify the output includes:

-a always,exit -F arch=b64 -S adjtimex,settimeofday,clock_settime -F key=time-change
-a always,exit -F arch=b32 -S adjtimex,settimeofday,clock_settime -F key=time-change
-w /etc/localtime -p wa -k time-change

32 Bit systems

Follow the same procedures as for 64 bit systems and ignore any entries with . In addition, also audit for the system call rule. For example: