ARST-RT-000050 - The Arista BGP router must be configured to reject outbound route advertisements for any prefixes that do not belong to any customers or the local autonomous system (AS).

Information

Advertisement of routes by an autonomous system for networks that do not belong to any of its customers pulls traffic away from the authorized network. This causes a denial of service (DoS) on the network that allocated the block of addresses and may cause a DoS on the network that is inadvertently advertising it as the originator. It is also possible that a misconfigured or compromised router within the GIG IP core could redistribute IGP routes into BGP, thereby leaking internal routes.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

This requirement is not applicable for the DODIN backbone.

Configure all Arista eBGP routers to filter outbound route advertisements for prefixes that are not allocated to or belong to any customer or the local AS.

Configure the Arista router to deny outbound route advertisements for any prefix belonging to the local AS Boundary.

Step 1: Configure the prefix lists.

LEAF-1A(config)#ip prefix-list ADVERTISE_ROUTES
LEAF-1A(config-ip-pfx)#seq 10 permit 10.12.0.0/16
LEAF-1A(config-ip-pfx)#seq 20 deny 10.17.0.0/16
LEAF-1A(config-ip-pfx)#seq 30 deny 10.23.0.0/16
LEAF-1A(config-ip-pfx)#seq 40 deny 10.47.0.0/16
LEAF-1A(config-ip-pfx)#seq 50 deny 10.59.0.0/16
LEAF-1A(config-ip-pfx)#seq 100 deny 0.0.0.0/0 le 32

Step 2: Configure the prefix lists outbound to the appropriate BGP neighbor.

LEAF-1A(config)#router bgp 65001
LEAF-1A(config-router-bgp)#neighbor 100.2.1.1 prefix-list ADVERTISE_ROUTES out

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Arista_MLS_EOS_4-2x_Y24M07_STIG.zip

Item Details

Category: ACCESS CONTROL

References: 800-53|AC-4, CAT|II, CCI|CCI-001368, Rule-ID|SV-255991r882315_rule, STIG-ID|ARST-RT-000050, Vuln-ID|V-255991

Plugin: Arista

Control ID: 8f10b6ed22b63a4dc3ca08d804c345504e18c8b7f4f3f2b5a0de4da28b0e75fc