Detections
Analytics
CISC-RT-000550 - The Cisco BGP switch must be configured to reject route advertisements from CE switches with an originating AS in the AS_PATH attribute that does not belong to that customer.
Information
Verifying the path a route has traversed will ensure that the local AS is not used as a transit network for unauthorized traffic. To ensure that the local AS does not carry any prefixes that do not belong to any customers, all PE switches must be configured to reject routes with an originating AS other than that belonging to the customer.Solution
Configure the switch to reject updates from CE switches with an originating AS in the AS_PATH attribute that does not belong to that customer.Step 1: Configure the as-path ACL as shown in the example below:
SW1(config)#ip as-path access-list 10 permit ^yy$
SW1(config)#ip as-path access-list 10 deny .*
Step 2: Apply the as-path filter inbound as shown in the example below:
SW1(config)#router bgp xx
SW1(config-switch)#neighbor x.1.4.12 filter-list 10 in
See Also
https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XE_Switch_Y26M04_STIG.zip
Item Details
Audit Name: DISA Cisco IOS XE Switch RTR STIG v3r4
Category: ACCESS CONTROL
References: 800-53|AC-4(8), CAT|III, CCI|CCI-000032, Rule-ID|SV-221029r1137905_rule, STIG-ID|CISC-RT-000550, STIG-Legacy|SV-110879, STIG-Legacy|V-101775, Vuln-ID|V-221029
Plugin: Cisco
Control ID: b7ecb9dca768b09d70950a3694d05fcfb9f775ed25a8dfe3966148f73a2b9c6e