The Cisco switch must be configured to authenticate Network Time Protocol (NTP) sources using authentication with FIPS-compliant algorithms.

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.

Review the Cisco switch configuration to verify it authenticates NTP sources using authentication with FIPS-compliant algorithms as shown in the configuration example below:

show running-config ntp

ntp authentication-key 1 md5 xxxxxx ntp server 10.1.12.10 key 1 ntp trusted-key 1 ntp authenticate

Note: Cisco NX-OS is limited to MD5 for NTP authentication, and incurs a permanent finding as it is not FIPS compliant. MD5 partially reduces the risk but cannot fully mitigate it.

If the Cisco switch is not configured to authenticate NTP sources using authentication with FIPS-compliant algorithms, this is a finding.

Configure the Cisco switch to authenticate NTP sources using authentication with FIPS-compliant algorithms as shown in the example below:

SW1# configure terminal SW1(config)# feature ntp SW1(config)# ntp authentication-key 1 md5 xxxxxx SW1(config)# ntp trusted-key 1 SW1(config)# ntp authenticate SW1(config)# ntp server 10.1.12.10 key 1 SW1(config)# ntp commit SW1(config)# end SW1# copy running-config startup-config

Note: The ntp commit command can be omitted if CFS is not enabled for NTP.