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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-216540r879768_rule 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 2023-09-18

Details

Check Text ( C-17775r288306_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 md5 encrypted 030654090416
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-17772r288307_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 md5 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