Title

The Cisco ACI must be configured to authenticate all routing protocol messages using a NIST-validated FIPS 198-1 message authentication code algorithm. (Cat II impact)

Discussion

A rogue router could send a fictitious routing update to convince a site's perimeter router to send traffic to an incorrect or even a rogue destination. This diverted traffic could be analyzed to learn confidential information about the site's network or used to disrupt the network's ability to communicate with other networks. This is known as a "traffic attraction attack" and is prevented by configuring neighbor router authentication for routing updates. However, using clear-text authentication provides little benefit since an attacker can intercept traffic and view the authentication key. This would allow the attacker to use the authentication key in an attack. Since MD5 is vulnerable to "birthday" attacks and may be compromised, routing protocol authentication must use FIPS 198-1 validated algorithms and modules to encrypt the authentication key. This requirement applies to all IPv4 and IPv6 protocols that are used to exchange routing or packet forwarding information; this includes all Interior Gateway Protocols (such as OSPF, EIGRP, and IS-IS) and Exterior Gateway Protocols (such as BGP), MPLS-related protocols (such as LDP), and multicast-related protocols.

Check Content

If EIGRP, RIP, and IS-IS protocols are used (these protocols only support MD5 authentication), this is a finding. Review the switch configuration using the show bgp and show ospf commands to verify BGP and OSPF. The configuration should be similar to the example below: Key-Chain bgp_keys tcp Key 1 -- text 0 "070e234f" send-id 2 recv-id 2 cryptographic-algorithm hmac-sha256 send lifetime 3600 If authentication protocols that affects the routing or forwarding tables are not configured to use key chain (TCP-AO) authentication with 180 maximum lifetime, this is a finding.

Fix Text

Configure authentication for every protocol that affects the routing or forwarding tables to use key chain (TCP-AO) authentication. Use the following command on all supported control plane protocols. This typically includes protocols such as BGP and OSPF. The following are examples. Step 1: Create a TCP-AO key chain. apic1(config)# ip tcp ao key chain <KEY_CHAIN_NAME> apic1(config)# key <KEY-ID> apic1(config-tcpkey chain-tcpkey)# key-string <KEY> apic1(config-tcpkey chain-tcpkey)# recv-id <ID> apic1(config-tcpkey chain-tcpkey)# send-id <ID> apic1(config-tcpkey chain-tcpkey)# send-lifetime <value in seconds> apic1(config-tcpkey chain-tcpkey)# recv-lifetime <value in seconds> apic1(config-tcpkey chain-tcpkey)# cryptographic-algorithm hmac-sha256 Step 2: Configure BGP to use the key chain for authentication. apic1(config)# router bgp <AS_NUMBER> apic1(config-router)# neighbor <peer-IP> remote-ao <KEY-CHAIN-NAME> apic1(config-router)# ao <KEY_CHAIN_NAME> Step 3: Configure OSPF to use the key chain for authentication. apic1(config)# interface Ethernet1/1 apic1(config-if)# ip address <address or range> apic1(config-if)# ip ospf authentication key-chain <OSPF_KEY_CHAIN>

Additional Identifiers

Rule ID: SV-272078r1064585_rule

Vulnerability ID: V-272078

Group Title: SRG-NET-000168-RTR-000078

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.