cis-ubuntu1604-v200-2-1-1-3

name	cis-ubuntu1604-v200-2-1-1-3
description	Ensure chrony is configured
category	cis-networking
version	2.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-16.04","services"]
cis_id	2.1.1.3
cis_benchmark	CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

2.1.1.3 Ensure chrony is configured (Automated)

Description

chrony is a daemon which implements the Network Time Protocol (NTP) and is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More information on chrony can be found at http://chrony.tuxfamily.org/. chrony can be configured to be a client and/or a server.

Notes:

• If ntp or systemd-timesyncd are used, chrony should be removed and this section skipped
• This recommendation only applies if chrony is in use on the system
• Only one time synchronization method should be in use on the system

Rationale

If chrony is in use on the system proper configuration is vital to ensuring time synchronization is working properly.

Audit Procedure

Command Line

Verify that only one time synchronization method is in use on the system:

Run the following command to verify that ntp is not installed:

dpkg -s ntp | grep -E '(Status:|not installed)'

Run the following command to verify that systemd-timesyncd is masked:

systemctl is-enabled systemd-timesyncd

Verify that chrony is configured:

Run the following command and verify remote server is configured properly:

grep -E "^(server|pool)" /etc/chrony/chrony.conf

Run the following command and verify the first field for the chronyd process is _chrony:

ps -ef | grep chronyd

Expected Result

• ntp should not be installed: dpkg-query: package 'ntp' is not installed and no information is available
• systemd-timesyncd should be masked
• chrony.conf should show configured server(s): server <remote-server>
• chronyd process should run as _chrony user

Note: The compiled-in default value is _chrony

Remediation

Command Line

Remove and/or disable additional time synchronization methods:

Run the following command to remove ntp:

apt purge ntp

Run the following command to stop and mask systemd-timesyncd:

systemctl --now mask systemd-timesyncd