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V-207154

CAT II (Medium)

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

Rule ID

SV-207154r856638_rule

STIG

Router Security Requirements Guide

Version

V5R2

CCIs

CCI-002385

Discussion

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.

Check Content

Review the device configuration to determine if controls have been defined to ensure the router does not send ICMP Mask Reply messages out to any external interfaces.

If ICMP Mask Reply messages are enabled on any external interfaces, this is a finding.

Fix Text

Disable ICMP mask replies on all external interfaces.