The Cisco ACI must be configured to have Internet Control Message Protocol (ICMP) mask replies disabled on all external interfaces.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-272087 | CACI-RT-000027 | SV-272087r1113993_rule | CCI-002385 | medium |
| Description | ||||
| The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Mask Reply ICMP messages are commonly used by attackers for network mapping and diagnosis. | ||||
| STIG | Date | |||
| Cisco ACI Router Security Technical Implementation Guide | 2025-06-18 | |||
Details
Check Text (C-272087r1113993_chk)
Review the router configuration and verify the ip mask-reply command is not enabled on any external interfaces as shown in the example below:
apic1(config)# interface Ethernet0/1
apic(config-if)# no ip icmp mask-reply
If the ip mask-reply command is configured on any external interface, this is a finding.
Fix Text (F-76044r1063657_fix)
Disable ip mask-reply on all external interfaces as shown below:
apic1(config)# interface Ethernet0/1
apic(config-if)# no ip icmp mask-reply