The Cisco router must be configured to have Internet Control Message Protocol (ICMP) mask reply messages disabled on all external interfaces.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-216747 | CISC-RT-000180 | SV-216747r856438_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 IOS XR Router RTR Security Technical Implementation Guide | 2024-08-22 | |||
Details
Check Text (C-216747r856438_chk)
Review the router configuration and verify that ipv4 mask-reply command is not enabled on any external interfaces as shown in the example below.
interface GigabitEthernet0/0/0/1
ipv4 address x.11.1.2 255.255.255.252
ipv4 mask-reply
If the router configuration has the ipv4 mask-reply command is enabled on any external interfaces, this is a finding.
Fix Text (F-17977r288631_fix)
Disable ipv4 mask-reply on all external interfaces as shown below.
RP/0/0/CPU0:R3(config)#int g0/0/0/1
RP/0/0/CPU0:R3(config-if)#no ipv4 mask-reply