V-283904

Discussion

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. A misconfigured or compromised router within the Department of Defense Information Network (DODIN) IP core could redistribute Interior Gateway Protocol (IGP) routes into BGP, thereby leaking internal routes.

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This requirement is not applicable for the DODIN Backbone. 

Review the router configuration to verify a filter is defined to only advertise routes for prefixes that belong to any customers or the local AS.

Use the command below to view the prefix list:

- show router policy prefix-list "Customer Prefix"

prefix 192.168.100.0/24 prefix-length-range 24-32
prefix 192.168.200.0/24 prefix-length-range 24-32

Use the command below to view the policy statement:

- show router policy "Advertise Customer"
    entry 10
        from
            prefix-list "Advertise Customer"
        exit
        action accept
        exit
    exit
    default-action drop
    exit

Use the command below to verify the policy is applied to the eBGP group:

- show router bgp group "eBGP" detail | match "Export Policy"

Export Policy    : Advertise Customer

If the router is not configured to reject outbound route advertisements that belong to any customers or the local AS, this is a finding.