The Cisco router must be configured to authenticate NTP sources using authentication that is cryptographically based.
An XCCDF Rule
Description
<VulnDiscussion>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.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-216540r879768_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
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