The Cisco router must be configured to authenticate NTP sources using authentication that is cryptographically based.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-216540 | CISC-ND-001150 | SV-216540r1107163_rule | CCI-001967 | medium |
| Description | ||||
| If Network Time Protocol 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. | ||||
| STIG | Date | |||
| Cisco IOS XR Router NDM Security Technical Implementation Guide | 2025-05-19 | |||
Details
Check Text (C-216540r1107163_chk)
Review the Cisco router configuration to verify that it is compliant with this requirement as shown in the configuration example below.
ntp
authentication-key 1 hmac-sha2-256 xxxxxx
trusted-key 1
server x.x.x.x key 1
server y.y.y.y key 1
If the Cisco router is not configured to authenticate NTP sources using authentication that is cryptographically based, this is a finding.
Fix Text (F-17772r1107162_fix)
Configure the Cisco router to authenticate NTP sources using authentication that is cryptographically based as shown in the example below.
RP/0/0/CPU0:R4#ntp authenticate
RP/0/0/CPU0:R4#ntp authentication-key 1 hmac-sha2-256 xxxxxx
RP/0/0/CPU0:R4#ntp trusted-key
RP/0/0/CPU0:R4#ntp server x.x.x.x key 1
RP/0/0/CPU0:R4#ntp server y.y.y.y key 1