The router must protect an enclave connected to an Alternate Gateway by using an inbound filter that only permits packets with destination addresses within the sites address space.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-55733	SRG-NET-000019-RTR-000009	SV-69987r1_rule		Medium

Description
Enclaves with Alternate Gateway connections must take additional steps to ensure there is no compromise on the enclave network or NIPRNet. Without verifying the destination address of traffic coming from the site's Alternate Gateway, the perimeter router could be routing transit data from the Internet into the NIPRNet. This could also make the perimeter router vulnerable to a DoS attack as well as provide a backdoor into the NIPRNet. The DoD enclave must ensure the ingress filter applied to external interfaces on a perimeter router connecting to an Approved Gateway is secure through filters permitting packets with a destination address belonging to the DoD enclave's address block.

Description

Enclaves with Alternate Gateway connections must take additional steps to ensure there is no compromise on the enclave network or NIPRNet. Without verifying the destination address of traffic coming from the site's Alternate Gateway, the perimeter router could be routing transit data from the Internet into the NIPRNet. This could also make the perimeter router vulnerable to a DoS attack as well as provide a backdoor into the NIPRNet. The DoD enclave must ensure the ingress filter applied to external interfaces on a perimeter router connecting to an Approved Gateway is secure through filters permitting packets with a destination address belonging to the DoD enclave's address block.

STIG	Date
Router Security Requirements Guide	2016-07-01

Details

Check Text ( C-56301r1_chk )
Review the configuration of each router interface connecting to an Alternate Gateway. Verify each permit statement of the ingress filter only permits packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the Alternate Gateway network service provider. If the ingress filter permits packets with addresses other than those specified, such as destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the Alternate Gateway network service provider, this is a finding.

Check Text ( C-56301r1_chk )

Review the configuration of each router interface connecting to an Alternate Gateway.

Verify each permit statement of the ingress filter only permits packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the Alternate Gateway network service provider.

If the ingress filter permits packets with addresses other than those specified, such as destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the Alternate Gateway network service provider, this is a finding.

Fix Text (F-60603r1_fix)
Configure the ingress filter of the perimeter router connected to an Alternate Gateway to only permit packets with destination addresses of the site's NIPRNet address space or a destination address belonging to the address block assigned by the Alternate Gateway network service provider.