The Cisco ASA must be configured to authenticate Network Time Protocol sources using authentication that is cryptographically based.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-239929 | CASA-ND-001080 | SV-239929r1107149_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 ASA NDM Security Technical Implementation Guide | 2025-05-19 |
Details
| Check Text (C-43162r1107147_chk) |
| Review the Cisco ASA 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 ntp authenticate ntp trusted-key 1 ntp server 10.1.12.2 key 1 prefer ntp server 10.1.48.10 key 1 Note: For ASAs running on Firepower Chassis hardware, the NTP settings are visible in the FXOS web UI only (not in the ASA CLI or ASDM web UI). If the Cisco ASA is not configured to authenticate NTP sources using authentication that is cryptographically based, this is a finding. |
| Fix Text (F-43121r1107148_fix) |
| 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 hmac-sha2-256 xxxxxx ASA(config)# ntp trusted-key 1 ASA(config)# ntp server 10.1.12.2 key 1 prefer ASA(config)# ntp server 10.1.48.10 key 1 ASA(config)# end |