Check: CISC-RT-000250
Cisco IOS XE Router RTR STIG:
CISC-RT-000250
(in versions v2 r9 through v1 r2)
Title
The Cisco perimeter router must be configured to enforce approved authorizations for controlling the flow of information between interconnected networks in accordance with applicable policy. (Cat II impact)
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.
Check Content
Review the router configuration to verify that ACLs are configured to allow or deny traffic for specific source and destination addresses as well as ports and protocols. In the example below, the router is peering BGP with DISN. ICMP echo and echo-reply packets are allowed for troubleshooting connectivity. WWW traffic is permitted inbound to the NIPRNet host-facing web server (x.12.1.22). interface GigabitEthernet0/1 description Link to DISN ip address x.12.1.10 255.255.255.0 ip access-group FILTER_PERIMETER in … … … ip access-list extended FILTER_PERIMETER permit tcp any any established permit tcp host x.12.1.9 host x.12.1.10 eq bgp permit tcp host x.12.1.9 eq bgp host x.12.1.10 permit icmp host x.12.1.9 host x.12.1.10 echo permit icmp host x.12.1.9 host x.12.1.10 echo-reply permit tcp any host x.12.1.22 eq www deny ip any any log-input If the router is not configured to enforce approved authorizations for controlling the flow of information between interconnected networks, this is a finding.
Fix Text
This requirement is not applicable for the DODIN Backbone. Step 1: Configure an ACL to allow or deny traffic as shown in the example below. R1(config)#ip access-list extended FILTER_PERIMETER R1(config-ext-nacl)#permit tcp any any established R1(config-ext-nacl)#permit tcp host x.12.1.9 host x.12.1.10 eq bgp R1(config-ext-nacl)#permit tcp host x.12.1.9 eq bgp host x.12.1.10 R1(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo R1(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo-reply R1(config-ext-nacl)#permit tcp any host x.12.1.22 eq www R1(config-ext-nacl)#deny ip any any log-input R1(config-ext-nacl)#exit Step 2: Apply the ACL inbound on all external interfaces. R2(config)#int g0/0 R1(config-if)#ip access-group FILTER_PERIMETER in
Additional Identifiers
Rule ID: SV-216663r531086_rule
Vulnerability ID: V-216663
Group Title: SRG-NET-000019-RTR-000002
Expert Comments
CCIs
Number | Definition |
---|---|
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. |
Controls
Number | Title |
---|---|
AC-4 |
Information Flow Enforcement |