Cisco IOS XE Release 3 RTR STIG Version Comparison

There are 20 differences between versions v1 r2 (June 28, 2017) (the "left" version) and v1 r5 (Jan. 25, 2019) (the "right" version).

Check CISR-RT-000001 was changed between these two versions. Green, underlined text was added, red, struck-out text was removed.

The regular view of the left check and right check may be easier to read.

Title

The Cisco IOS XE ISR 4000 Series router must enforce approved authorizations for controlling the flow of information between interconnected networks in accordance with applicable policy.

Check Content

Review the Cisco IOS XE ISR 4000 Series router configuration. Verify configuration and verify that the external interface blocks inbound traffic with a source IP address belonging to the internal network. The configuration should look similar to the example below where the private IP address space is 1.1.1.0/24: interface FastEthernet 0/0 description NIPRNet link ip address x.x.x.x 255.255.255.0 ip access-group INGRESS_ACL in ... ip access-list extended INGRESS_ACL deny ip 1.1.1.0 0.0.0.255 any log ... If the external interface of the Cisco IOS XE ISR 4000 Series router has not been configured to block all inbound packets with a source IP address belonging to the private network, this is a finding.

Discussion

Information flow control regulates authorized information to travel within a network and between interconnected networks. Controlling the flow of network traffic is critical so it does not introduce any unacceptable risk to the network infrastructure or data. An example of a flow control restriction is blocking outside traffic claiming to be from within the organization. For most routers, internal information flow control is a product of system design.

Fix

Configure the Cisco IOS XE ISR 4000 Series router to block all inbound packets with a source IP address belonging to the private network. The configuration would look similar to the example below: interface FastEthernet 0/0 description NIPRNet link ip address x.x.x.x 255.255.255.0 ip access-group INGRESS_ACL in ... ip access-list extended INGRESS_ACL deny ip 1.1.1.0 0.0.0.255 any log ...