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

Associated with: CCI-002385

SV-92931r1_rule The router must be configured to have Internet Control Message Protocol (ICMP) mask replies disabled on all external interfaces.

Vulnerability 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.

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