The Ubuntu operating system must compare internal information system clocks at least every 24 hours with a server which is synchronized to an authoritative time source, such as the United States Naval Observatory (USNO) time servers, or a time server designated for the appropriate DoD network (NIPRNet/SIPRNet), and/or the Global Positioning System (GPS).

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-215116	UBTU-16-030100	SV-215116r508033_rule		Medium

Description
Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate. Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Organizations should consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints).

Description

Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate. Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Organizations should consider endpoints that may not have regular access to the authoritative time server (e.g., mobile, teleworking, and tactical endpoints).

STIG	Date
Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide	2020-09-03

Details

Check Text ( C-16315r466240_chk )
The system clock must be configured to compare the system clock at least every 24 hours to the authoritative time source. Note: If the system is not networked this item is Not Applicable. The value of [source] should be an authoritative DoD time source. Verify that "Chrony" is active and enabled by running the following command: # sudo systemctl status chrony.service chrony.service - LSB: Controls chronyd NTP time daemon Loaded: loaded (/etc/init.d/chrony; bad; vendor preset: enabled) Active: active (running) since Wed 2020-01-08 14:01:47 EST; 50min ago Docs: man:systemd-sysv-generator(8) If "chrony.service" is not "loaded", this is a finding. If "chrony.service" is not "active (running)", this is a finding. Verify that the "chrony.conf" file is configured to an authoritative DoD time source by running the following command: # grep -i ^server /etc/chrony/chrony.conf server [source] iburst maxpoll 17 If the parameter "server" is not set, is not set to an authoritative DoD time source, or is commented out, this is a finding. Check the value of "maxpoll" in the "/etc/chrony/chrony.conf" file with the following command: # sudo grep -i maxpoll /etc/chrony/chrony.conf server [source] iburst maxpoll 17 If "maxpoll" is not set to "17" or does not exist, this is a finding.

Check Text ( C-16315r466240_chk )

The system clock must be configured to compare the system clock at least every 24 hours to the authoritative time source.

Note: If the system is not networked this item is Not Applicable. The value of [source] should be an authoritative DoD time source.

Verify that "Chrony" is active and enabled by running the following command:

# sudo systemctl status chrony.service

chrony.service - LSB: Controls chronyd NTP time daemon
Loaded: loaded (/etc/init.d/chrony; bad; vendor preset: enabled)
Active: active (running) since Wed 2020-01-08 14:01:47 EST; 50min ago
Docs: man:systemd-sysv-generator(8)

If "chrony.service" is not "loaded", this is a finding.
If "chrony.service" is not "active (running)", this is a finding.

Verify that the "chrony.conf" file is configured to an authoritative DoD time source by running the following command:

# grep -i ^server /etc/chrony/chrony.conf

server [source] iburst maxpoll 17

If the parameter "server" is not set, is not set to an authoritative DoD time source, or is commented out, this is a finding.

Check the value of "maxpoll" in the "/etc/chrony/chrony.conf" file with the following command:

# sudo grep -i maxpoll /etc/chrony/chrony.conf

server [source] iburst maxpoll 17

If "maxpoll" is not set to "17" or does not exist, this is a finding.

Fix Text (F-16313r466241_fix)
Note: If the system is not networked this item is Not Applicable. To configure the system clock to compare the system clock at least every 24 hours to the authoritative time source, edit the "/etc/chrony/chrony.conf" file. Add or correct the following lines, by replacing "[source]" in the following line with an authoritative DoD time source: server [source] iburst maxpoll 17 If the "chrony" service was running and the value of "maxpoll" or "server" was updated, then the service must be restarted using the following command: # sudo systemctl restart chrony.service If the "chrony" service was not running then it must be started: # sudo systemctl start chrony.service

Fix Text (F-16313r466241_fix)

Note: If the system is not networked this item is Not Applicable.

To configure the system clock to compare the system clock at least every 24 hours to the authoritative time source, edit the "/etc/chrony/chrony.conf" file.

Add or correct the following lines, by replacing "[source]" in the following line with an authoritative DoD time source:

server [source] iburst maxpoll 17

If the "chrony" service was running and the value of "maxpoll" or "server" was updated, then the service must be restarted using the following command:

# sudo systemctl restart chrony.service

If the "chrony" service was not running then it must be started:

# sudo systemctl start chrony.service