CISC-RT-000170 - The Cisco router must be configured to have Internet Control Message Protocol (ICMP) unreachable messages disabled on all external interfaces.

Information

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. Host unreachable ICMP messages are commonly used by attackers for network mapping and diagnosis.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

Disable ip unreachables 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)#ipv4 unreachables disable

Alternative - DODIN Backbone

Configure the PE router to rate limit ICMP unreachable messages as shown in the example below.

RP/0/0/CPU0:R3(config)#icmp ipv4 rate-limit unreachable df 1000
RP/0/0/CPU0:R3(config)#icmp ipv4 rate-limit unreachable 60000
RP/0/0/CPU0:R3(config)#end

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XR_Router_Y24M07_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-5, CAT|II, CCI|CCI-002385, Rule-ID|SV-216746r856437_rule, STIG-ID|CISC-RT-000170, STIG-Legacy|SV-105837, STIG-Legacy|V-96699, Vuln-ID|V-216746

Plugin: Cisco

Control ID: 2386852b1332c0d0dea9cec3e7f109a5c586a2a142f1e6d584170f10b077e9c4