The operating system must, for networked systems, compare internal information system clocks at least every 24 hours with a server which is synchronized to one of the redundant 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).

From Apple OS X 10.9 (Mavericks) Workstation Security Technical Implementation Guide

Associated with: CCI-001891

SV-72757r1_rule The operating system must, for networked systems, compare internal information system clocks at least every 24 hours with a server which is synchronized to one of the redundant 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).

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 of 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).

Check content

The Network Time Protocol (NTP) service must be enabled on all networked systems. To check if the service is running, use the following command: sudo launchctl list | grep org.ntp.ntpd If nothing is returned, this is a finding. To ensure that an authorized NTP server is configured, run the following command or examine /etc/ntp.conf: sudo grep ^server /etc/ntp.conf Only approved time servers should be configured for use. If no server is configured, or if an unapproved time server is in use, this is a finding.

Fix text

To enable the NTP service, run the following command: sudo launchctl load -w /System/Library/LaunchDaemons/org.ntp.ntpd.plist To configure one or more time servers for use, edit /etc/ntp.conf and enter each hostname or ip address on a separate line, prefixing each one with the keyword "server".

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