cis-ubuntu2004-v300-6-3-3-4

name	cis-ubuntu2004-v300-6-3-3-4
description	Ensure events that modify date and time information are collected
category	cis-logging
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","auditing","auditd"]
cis_id	6.3.3.4
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

6.3.3.4 Ensure events that modify date and time information are collected (Automated)

Profile

• 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 Procedure

Command Line

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 output of matches:

-a always,exit -F arch=b64 -S adjtimex,settimeofday -k time-change
-a always,exit -F arch=b32 -S adjtimex,settimeofday -k time-change
-a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -k time-change
-a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -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 -F key=time-change
-a always,exit -F arch=b32 -S settimeofday,adjtimex -F key=time-change
-a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-change
-a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-change
-w /etc/localtime -p wa -k time-change