Check: CISC-RT-000540
Cisco IOS Router RTR STIG:
CISC-RT-000540
(in versions v2 r6 through v1 r0.1)
Title
The Cisco 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. By default Cisco IOS enforces the first AS in the AS_PATH attribute for all route advertisements. Review the router configuration to verify that the command no bgp enforce-first-as is not configured. router bgp xx no synchronization no 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. R1(config)#router bgp xx R1(config-router)#bgp enforce-first-as
Additional Identifiers
Rule ID: SV-216602r531085_rule
Vulnerability ID: V-216602
Group Title: SRG-NET-000018-RTR-000006
Expert Comments
CCIs
Number | Definition |
---|---|
CCI-000032 |
The information system enforces information flow control using organization-defined security policy filters as a basis for flow control decisions for organization-defined information flows. |
Controls
Number | Title |
---|---|
AC-4 (8) |
Security Policy Filters |