The Cisco switch must be configured to use encryption for routing protocol authentication.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-220989	CISC-RT-000040	SV-220989r894624_rule		Medium

Description

A rogue switch could send a fictitious routing update to convince a site's perimeter switch 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 switch 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. 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.

STIG	Date
Cisco IOS XE Switch RTR Security Technical Implementation Guide	2023-02-28

Details

Check Text ( C-22704r894622_chk )

Review the switch configuration. For every routing protocol that affects the routing or forwarding tables, verify that the switch is encrypting the authentication key as shown in the examples below: BGP Example: key chain tcp key send-id recv-id cryptographic-algorithm hmac-sha-1 key-string accept-lifetime 00:00:00 Jan 1 2022 duration 180 send-lifetime 00:00:00 Jan 1 2022 duration 180 ! ! router bgp no synchronization bgp log-neighbor-changes neighbor x.x.x.x remote-as neighbor x.x.x.x ao Note: BGP uses key chains and TCP-AO to replace MD5. EIGRP Example: interface GigabitEthernet1/0 no switchport ip address x.x.x.x 255.255.255.0 ip authentication mode eigrp 1 md5 ip authentication key-chain eigrp 1 EIGRP_KEY_CHAIN IS-IS Example: interface GigabitEthernet1/0 no switchport ip address x.x.x.x 255.255.255.0 ip router isis isis authentication mode md5 isis authentication key-chain ISIS_KEY_CHAIN OSPF Example: key chain OSPF_KEY_CHAIN key 1 key-string xxxxxxx cryptographic-algorithm hmac-sha-256 … … … interface GigabitEthernet0/1 ip address x.x.x.x 255.255.255.0 ip ospf authentication key-chain OSPF_KEY_CHAIN RIP Example: interface GigabitEthernet1/0 no switchport ip rip authentication mode md5 ip rip authentication key-chain RIP_KEY_CHAIN If the routing protocol is not encrypting the authentication key, this is a finding.

Fix Text (F-22693r894623_fix)

Configure all routing protocol authentications to encrypt the authentication key. BGP Example: Step 1: Configure a keychain for TCP-AO. key chain tcp key send-id recv-id cryptographic-algorithm hmac-sha-1 key-string accept-lifetime 00:00:00 Jan 1 2022 duration 180 send-lifetime 00:00:00 Jan 1 2022 duration 180 ! Step 2: Configure BGP autonomous system. router bgp no synchronization bgp log-neighbor-changes neighbor x.x.x.x remote-as neighbor x.x.x.x ao EIGRP Example: SW2(config)#int g0/1 SW2(config-if)#ip authentication mode eigrp 1 md5 SW2(config-if)#ip authentication key-chain eigrp 1 EIGRP_KEY_CHAIN IS-IS Example: SW1(config)#int g0/1 SW1(config-if)#isis authentication mode md5 SW1(config-if)#isis authentication key-chain ISIS_KEY_CHAIN OSPF Example: SW1(config)#key chain OSPF_KEY_CHAIN SW1(config-keychain)#key 1 SW1(config-keychain-key)#key-string xxxxxx SW1(config-keychain-key)#cryptographic-algorithm hmac-sha-256 SW1(config-keychain-key)#exit SW1(config-keychain-key)#end SW1(config)#interface GigabitEthernet0/2 SW1(config-if)#ip ospf authentication key-chain OSPF_KEY_CHAIN RIP Example: SW2(config)#int g1/0 SW2(config-if)#ip rip authentication mode md5 SW2(config-if)#ip rip authentication key-chain RIP_KEY_CHAIN