Title

The Juniper BGP router must be configured to reject route advertisements from BGP peers that do not list their autonomous system (AS) number as the first AS in the AS_PATH attribute. (Cat III impact)

Discussion

Verifying the path a route has traversed will ensure the IP core is not used as a transit network for unauthorized or possibly even Internet traffic. All autonomous system boundary routers (ASBRs) must ensure updates received from eBGP peers list their AS number as the first AS in the AS_PATH attribute.

Check Content

Review the router configuration to verify the router is configured to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute. Verify that the enforce-first-as command has been configured at the BGP or group hierarchy as shown in the example below: protocols { … … … bgp { enforce-first-as; If the router is not configured to reject updates from peers that do not list their AS number as the first AS in the AS_PATH attribute, this is a finding.

Fix Text

Configure the router to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute using the enforce-first-as command as shown in the example below: [edit protocols bgp group] set enforce-first-as

Additional Identifiers

Rule ID: SV-217058r945854_rule

Vulnerability ID: V-217058

Group Title: SRG-NET-000018-RTR-000006

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.