Information
The Cisco switch must be configured to authenticate Network Time Protocol (NTP) sources using authentication that is cryptographically based.
GROUP ID: V-220606
RULE ID: SV-220606r1107157
If NTP is not authenticated, an attacker can introduce a rogue NTP server. This rogue server can then be used to send incorrect time information to network devices, which will make log timestamps inaccurate and affect scheduled actions.
NTP authentication is used to prevent this tampering by authenticating the time source.
Solution
Configure the Cisco switch to authenticate NTP sources using authentication that is cryptographically based as shown in the example below:
SW2(config)#ntp authenticate
SW2(config)#ntp authentication-key 1 hmac-sha2-256 xxxxxx
SW2(config)#ntp trusted-key 1
SW2(config)#ntp server x.x.x.x key 1
SW2(config)#ntp server y.y.y.y key 1