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The Cisco BGP switch must be configured to reject outbound route advertisements for any prefixes belonging to the IP core.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-221027CISC-RT-000530SV-221027r929070_ruleCCI-001097medium
Description
Outbound route advertisements belonging to the core can result in traffic either looping or being black holed, or at a minimum, using a nonoptimized path.
STIGDate
Cisco IOS XE Switch RTR Security Technical Implementation Guide2025-05-20

Related Frameworks

1 mapping across 5 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (18) 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.

CFG-02Secure Baseline Configurations
1.00
CRY-01Use of Cryptographic Controls
1.00
CRY-01.1Alternate Physical Protection
1.00
CRY-03Transmission Confidentiality
1.00
CRY-04Transmission Integrity
1.00
CRY-05Encrypting Data At Rest
1.00
DCH-01Data Protection
1.00
IAC-21Least Privilege
1.00
MON-01Continuous Monitoring
1.00
MON-01.1Intrusion Detection & Prevention Systems (IDS & IPS)
1.00

+8 more (top 10 by confidence shown)

NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (10) 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.

CM-6Configuration Settings
1.00
SC-24Fail in Known State
1.00
SC-47Alternate Communications Paths
1.00
SC-5Denial-of-service Protection
1.00
SC-7Boundary Protection
1.00
SC-7(11)Restrict Incoming Communications Traffic
1.00
SC-7(29)Separate Subnets to Isolate Functions
1.00
SC-7(5)Deny by Default — Allow by Exception
1.00
SI-4System Monitoring
1.00
SI-4(11)Analyze Communications Traffic Anomalies
1.00
NIST 800-1710 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (3) 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.

3.13.1
1.00
3.13.2
1.00
3.13.5
1.00
CCI1 mapping
CCI-001097
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (5) 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.

DE.CM-01
1.00
PR.DS-01
1.00
PR.DS-02
1.00
PR.DS-10
1.00
PR.IR-01
1.00

Who does this work

15 NICE work roles and 9 EC-Council certifications.

This is an inference across published mappings, not a single claim by anyone. This check maps to a control, which maps to a Cybersecurity Framework outcome, which NIST assigns to the work roles below. EC-Council separately maps its certifications to those same roles.

A certification prepares someone for a role. It is not evidence that a holder is qualified, and neither NIST nor EC-Council has stated that any certification here addresses this check.

Work-role assignments published by NIST (NICE Framework Components 2.2.0 and the CSF 2.0 OLIR crosswalk). Certification mappings published by EC-Council.

Details

Check Text (C-221027r929070_chk)

Step 1: Verify that a prefix list has been configured containing prefixes belonging to the IP core. ip prefix-list FILTER_CORE_PREFIXES seq 5 deny x.1.1.0/24 le 32 ip prefix-list FILTER _CORE_PREFIXES seq 10 deny x.1.2.0/24 le 32 ip prefix-list FILTER _CORE_PREFIXES seq 15 permit 0.0.0.0/0 ge 8 Step 2: Verify that the prefix lists has been applied to all external BGP peers as shown in the example below: router bgp xx no synchronization bgp log-neighbor-changes neighbor x.1.4.12 remote-as yy address-family ipv4 neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out If the switch is not configured to reject outbound route advertisements for prefixes belonging to the IP core, this is a finding.

Fix Text (F-22731r929069_fix)

Step 1: Configure a prefix list for containing all customer and local AS prefixes as shown in the example below: R1(config)#ip prefix-list FILTER_CORE_PREFIXES deny x.1.1.0/24 le 32 R1(config)#ip prefix-list FILTER _CORE_PREFIXES deny x.1.2.0/24 le 32 R1(config)#ip prefix-list FILTER _CORE_PREFIXES permit 0.0.0.0/0 ge 8 Step 2: Apply the prefix list filter outbound to each CE neighbor as shown in the example. router bgp xx address-family ipv4 neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out