Detections
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1.52 CISC-RT-000500

Information

The Cisco BGP router must be configured to reject inbound route advertisements for any prefixes belonging to the local autonomous system (AS).

GROUP ID: V-216688
RULE ID: SV-216688r531086

Accepting route advertisements belonging to the local AS can result in traffic looping or being black-holed, or at a minimum, using a non-optimized path.

Solution

Configure the router to reject inbound route advertisements for any prefixes belonging to the local AS.

Step 1: Add to the prefix filter list those prefixes belonging to the local autonomous system.

R1(config)#ip prefix-list PREFIX_FILTER seq 74 deny x.13.1.0/24 le 32

Step 2: If not already completed to be compliant with previous requirement, apply the prefix list filter inbound to each external BGP neighbor as shown in the example.

R1(config)#router bgp xx
R1(config-router)#neighbor x.1.1.9 prefix-list PREFIX_FILTER in
R1(config-router)#neighbor x.2.1.7 prefix-list PREFIX_FILTER in

See Also

https://workbench.cisecurity.org/benchmarks/26261

Item Details

Category: ACCESS CONTROL

References: 800-53|AC-4, CAT|II, CCI|CCI-001368, Rule-ID|SV-216688r531086_rule, STIG-ID|CISC-RT-000500, Vuln-ID|V-216688

Plugin: Cisco

Control ID: 29a20ae2244130faad40ca9840deb9782e953faecba286dabef02fe817b3503c