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The Cisco router must be configured to have Internet Control Message Protocol (ICMP) redirect messages disabled on all external interfaces.


Overview

Finding ID Version Rule ID IA Controls Severity
V-216748 CISC-RT-000190 SV-216748r531087_rule 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. Redirect ICMP messages are commonly used by attackers for network mapping and diagnosis.
STIG Date
Cisco IOS XR Router RTR Security Technical Implementation Guide 2020-09-23

Details

Check Text ( C-17980r288633_chk )
Review the router configuration to verify that ipv4 redirects command has not been configured on any external interface as shown in the example below.

interface GigabitEthernet0/0/0/1
ipv4 address x.11.1.2 255.255.255.252
ipv4 redirects

If ICMP Redirect messages are enabled on any external interfaces, this is a finding.
Fix Text (F-17978r288634_fix)
Disable ICMP redirects on all external interfaces as shown in the example below.

RP/0/0/CPU0:R3(config)#int g0/0/0/1
RP/0/0/CPU0:R3(config-if)#no ipv4 redirects