The Cisco BGP switch 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.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-221028	CISC-RT-000540	SV-221028r945854_rule	CCI-000032	low
Description
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 switches (ASBRs) must ensure updates received from eBGP peers list their AS number as the first AS in the AS_PATH attribute.
STIG			Date
Cisco IOS XE Switch RTR Security Technical Implementation Guide			2025-05-20

Related Frameworks

1 mapping across 3 frameworks

SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (1) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

NET-04.7Policy Decision Point (PDP)

1.00

DISA STIG Benchmark (XCCDF)3intersects(normalised)
DISA CCI List2025-01-23equal to(normalised)
SCF Secure Traceability Relationship Mapping (STRM)2026.2equal to

NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (2) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

AC-4(8)Security and Privacy Policy Filters

1.00

DISA STIG Benchmark (XCCDF)3intersects(normalised)
DISA CCI List2025-01-23equal to(normalised)

CM-6Configuration Settings

1.00

DISA STIG Benchmark (XCCDF)3intersects(normalised)
DISA STIG Benchmark (XCCDF)2our copyintersects(normalised)
DISA STIG Benchmark (XCCDF)2intersects(normalised)
DISA CCI List2025-01-23equal to(normalised)

CCI1 mapping

CCI-000032

1.00

DISA STIG Benchmark (XCCDF)3intersects(normalised)

Details

Check Text (C-221028r945854_chk)

Review the switch configuration to verify the switch 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 switch 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 switch 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 (F-22732r408879_fix)

Configure the switch to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute. SW1(config)#router bgp xx SW1(config-switch)#bgp enforce-first-as