Vulnerability Discussion

Approved time servers must be the only servers configured for use.

This rule ensures the uniformity of time stamps for information systems with multiple system clocks and
systems connected over a network.

An authoritative time server is synchronized with redundant United States Naval Observatory (USNO) time
servers as designated for the appropriate DOD network.

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

Check

Verify the macOS system is configured to use an authorized time server with the following
command:

/usr/bin/osascript -l JavaScript << EOS
$.NSUserDefaults.alloc.initWithSuiteName('com.apple.MCX')\
.objectForKey('timeServer').js
EOS

If the result is not an authoritative time server which is synchronized with redundant United States
Naval Observatory (USNO) time servers as designated for the appropriate DoD network, this is a
finding.

Fix

Configure the macOS system to use an authorized time server by
installing the "com.apple.MCX" configuration profile.