The Cisco router must be configured to authenticate Network Time Protocol (NTP) sources using authentication with FIPS-compliant algorithms.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-215698 | SRG-APP-000395-NDM-000347 | CISC-ND-001150 | SV-215698r1156808_rule | 2025-12-08 | 3 |
| Description |
|---|
| If NTP 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. |
| ℹ️ Check |
|---|
| Review the Cisco router configuration to verify it authenticates NTP sources using authentication with FIPS-compliant algorithms as shown in the configuration example below: ntp authentication-key 1 md5 xxxxxx ntp authenticate ntp trusted-key 1 ntp server x.x.x.x key 1 ntp server y.y.y.y key 1 NOTE: Cisco IOS is limited to MD5 for NTP authentication, and incurs a permanent finding as it is not FIPS compliant. MD5 partially reduces the risk but cannot fully mitigate it. If the Cisco router is not configured to authenticate NTP sources using authentication with FIPS-compliant algorithms, this is a finding. |
| ✔️ Fix |
|---|
| Configure the Cisco router to authenticate NTP sources using authentication with FIPS-compliant algorithms as shown in the example below: R2(config)#ntp authenticate R2(config)#ntp authentication-key 1 md5 xxxxxx R2(config)#ntp trusted-key 1 R2(config)#ntp server x.x.x.x key 1 R2(config)#ntp server y.y.y.y key 1 |