The Cisco ASA must be configured to authenticate Network Time Protocol 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-239929r961506_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Configure the Cisco ASA to authenticate NTP sources using authentication that is cryptographically based as shown in the example below.
ASA(config)# ntp authenticate
ASA(config)# ntp authentication-key 1 md5 xxxxxxxxxx
ASA(config)# ntp trusted-key 1
ASA(config)# ntp server 10.1.12.2 key 1 prefer