The Red Hat Enterprise Linux operating system must, for networked systems, synchronize clocks with a server that is synchronized to one of the redundant United States Naval Observatory (USNO) time servers, a time server designated for the appropriate DoD network (NIPRNet/SIPRNet), and/or the Global Positioning System (GPS).

From Red Hat Enterprise Linux 7 Security Technical Implementation Guide

Associated with: CCI-001891 CCI-002046

SV-86893r3_rule The Red Hat Enterprise Linux operating system must, for networked systems, synchronize clocks with a server that is synchronized to one of the redundant United States Naval Observatory (USNO) time servers, a time server designated for the appropriate DoD network (NIPRNet/SIPRNet), and/or the Global Positioning System (GPS).

Vulnerability discussion

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).Satisfies: SRG-OS-000355-GPOS-00143, SRG-OS-000356-GPOS-00144

Check content

Check to see if NTP is running in continuous mode. # ps -ef | grep ntp If NTP is not running, this is a finding. If the process is found, then check the "ntp.conf" file for the "maxpoll" option setting: # grep maxpoll /etc/ntp.conf maxpoll 10 If the option is set to "17" or is not set, this is a finding. If the file does not exist, check the "/etc/cron.daily" subdirectory for a crontab file controlling the execution of the "ntpd -q" command. # grep -i "ntpd -q" /etc/cron.daily/* # ls -al /etc/cron.* | grep ntp ntp If a crontab file does not exist in the "/etc/cron.daily" that executes the "ntpd -q" command, this is a finding.

Fix text

Edit the "/etc/ntp.conf" file and add or update an entry to define "maxpoll" to "10" as follows: maxpoll 10 If NTP was running and "maxpoll" was updated, the NTP service must be restarted: # systemctl restart ntpd If NTP was not running, it must be started: # systemctl start ntpd

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