The Cisco router must be configured to authenticate NTP sources using authentication that is cryptographically based.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-216540 | SRG-APP-000395-NDM-000347 | CISC-ND-001150 | SV-216540r961506_rule | 2025-02-27 | 3 |
| 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. |
| ℹ️ Check |
|---|
| 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 |
|---|
| 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 |