Inbound IP packets using RFC 1918 address space (10.0.0.0/8, 172.16.0.0 /12, and 192.168.0 /16) must be blocked, denied, or dropped at the perimeter device.

From Perimeter L3 Switch Security Technical Implementation Guide

Part of RFC1918 addresses are not blocked

Associated with IA controls: ECSC-1

SV-15392r2_rule Inbound IP packets using RFC 1918 address space (10.0.0.0/8, 172.16.0.0 /12, and 192.168.0 /16) must be blocked, denied, or dropped at the perimeter device.

Vulnerability discussion

This type of IP address spoofing occurs when someone outside the network uses an RFC1918 address to gain access to systems or devices on the internal network. If the intruder is successful, they can intercept data, passwords, etc., and use that information to perform destructive acts on or to the network.

Check content

Review the perimeter device configuration to ensure access control lists are configured to block, deny, or drop inbound IP addresses using the RFC1918 IP address space of 10.0.0.0/8, 172.16.0.0 /12, and 192.168.0 /16. Depending on the security posture of the access control list, this requirement may be met explicitly or inexplicitly.

Fix text

Configure the perimeter device to ensure access control lists are configured to block, deny, or drop inbound IP addresses using the RFC1918 IP address space of 10.0.0.0/8, 172.16.0.0 /12, and 192.168.0 /16. Depending on the security posture of the access control list, this requirement may be met explicitly or inexplicitly.

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