STIGQter: STIG Summary: Cisco IOS XR Router RTR Security Technical Implementation Guide Version: 2 Release: 1 Benchmark Date: 23 Oct 2020:

The Cisco perimeter router must be configured to 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.

DISA Rule

SV-216756r531087_rule

Vulnerability Number

V-216756

Group Title

SRG-NET-000019-RTR-000008

Rule Version

CISC-RT-000280

Severity

CAT I

CCI(s)

• CCI-001414 - The information system enforces approved authorizations for controlling the flow of information between interconnected systems based on organization-defined information flow control policies.

Weight

10

Fix Recommendation

This requirement is not applicable for the DODIN Backbone.

Step 1: Configure the ingress ACL 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 as shown in the example below.

RP/0/0/CPU0:R2(config)#ip access-list ISP_ACL_INBOUND
RP/0/0/CPU0:R2(config-ipv4-acl)#permit tcp any any established
RP/0/0/CPU0:R2(config-ipv4-acl)#permit icmp host x.12.1.16 host x.12.1.17 echo
RP/0/0/CPU0:R2(config-ipv4-acl)#permit icmp host x.12.1.16 host x.12.1.17 echo-reply
RP/0/0/CPU0:R2(config-ipv4-acl)#permit tcp any host x.12.1.22 eq www
RP/0/0/CPU0:R2(config-ipv4-acl)#permit tcp any host x.12.1.23 eq www
RP/0/0/CPU0:R2(config-ipv4-acl)#permit 50 any host x.12.1.24
RP/0/0/CPU0:R2(config-ipv4-acl)#permit 51 any host x.12.1.24
RP/0/0/CPU0:R2(config-ipv4-acl)#deny ip any any log-input
RP/0/0/CPU0:R2(config-ipv4-acl)#end

Step 2: Apply the ACL inbound on the ISP-facing interface.

RP/0/0/CPU0:R3(config)#int g0/0/0/2
RP/0/0/CPU0:R3(config-if)#ipv4 access-group ISP_ACL_INBOUND in
RP/0/0/CPU0:R3(config-if)#end

Check Contents

This requirement is not applicable for the DODIN Backbone.

Step 1: Verify the interface connecting to ISP has an inbound ACL as shown in the example below.

interface GigabitEthernet0/0/0/2
description Link to ISP
ipv4 address x.22.1.15 255.255.255.252
ipv4 access-group ISP_ACL_INBOUND ingress

Step 2: Verify that the ACL only allows traffic to specific destination addresses (i.e. enclave’s NIPRNet address space) as shown in the example below.

ipv4 access-list ISP_ACL_INBOUND
10 permit tcp any any established
20 permit icmp host x.12.1.16 host x.12.1.17 echo
30 permit icmp host x.12.1.16 host x.12.1.17 echo-reply
40 permit tcp any host x.12.1.22 eq www
50 permit tcp any host x.12.1.23 eq www
60 permit esp any host x.12.1.24
70 permit ahp any host x.12.1.24
80 deny ipv4 any any log-input

Note: An Approved Gateway (AG) is any external connection from a DoD NIPRNet enclave to an Internet Service Provider, or network owned by a contractor, or non-DoD federal agency that has been approved by either the DoD CIO or the DoD Component CIO. This AG requirement does not apply to commercial cloud connections when the Cloud Service Provider (CSP) network is connected via the NIPRNet Boundary Cloud Access Point (BCAP).

If the ingress ACL bound to the interface connecting to an alternate gateway 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.

Vulnerability Number

V-216756

Documentable

False

Rule Version

CISC-RT-000280

Severity Override Guidance

This requirement is not applicable for the DODIN Backbone.

Step 1: Verify the interface connecting to ISP has an inbound ACL as shown in the example below.

interface GigabitEthernet0/0/0/2
description Link to ISP
ipv4 address x.22.1.15 255.255.255.252
ipv4 access-group ISP_ACL_INBOUND ingress

Step 2: Verify that the ACL only allows traffic to specific destination addresses (i.e. enclave’s NIPRNet address space) as shown in the example below.

ipv4 access-list ISP_ACL_INBOUND
10 permit tcp any any established
20 permit icmp host x.12.1.16 host x.12.1.17 echo
30 permit icmp host x.12.1.16 host x.12.1.17 echo-reply
40 permit tcp any host x.12.1.22 eq www
50 permit tcp any host x.12.1.23 eq www
60 permit esp any host x.12.1.24
70 permit ahp any host x.12.1.24
80 deny ipv4 any any log-input

Note: An Approved Gateway (AG) is any external connection from a DoD NIPRNet enclave to an Internet Service Provider, or network owned by a contractor, or non-DoD federal agency that has been approved by either the DoD CIO or the DoD Component CIO. This AG requirement does not apply to commercial cloud connections when the Cloud Service Provider (CSP) network is connected via the NIPRNet Boundary Cloud Access Point (BCAP).

If the ingress ACL bound to the interface connecting to an alternate gateway 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 Content Reference

M

Target Key

4029

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