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The Cisco BGP switch must be configured to reject inbound route advertisements from a customer edge (CE) switch for prefixes that are not allocated to that customer.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-221025CISC-RT-000510SV-221025r622190_ruleCCI-001368medium
Description
As a best practice, a service provider should only accept customer prefixes that have been assigned to that customer and any peering autonomous systems. A multi-homed customer with BGP speaking switches connected to the Internet or other external networks could be breached and used to launch a prefix de-aggregation attack. Without ingress route filtering of customers, the effectiveness of such an attack could impact the entire IP core and its customers.
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 (17) 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.

AST-04Network Diagrams & Data Flow Diagrams (DFDs)
1.00
AST-04.2Control Applicability Boundary Graphical Representation
1.00
CFG-02Secure Baseline Configurations
1.00
CRY-01Use of Cryptographic Controls
1.00
DCH-01Data Protection
1.00
DCH-19Geographic Location of Data
1.00
END-01Endpoint Device Management (EDM)
1.00
END-04Malicious Code Protection (Anti-Malware)
1.00
END-06Endpoint File Integrity Monitoring (FIM)
1.00
IAC-21Least Privilege
1.00

+7 more (top 10 by confidence shown)

NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (42) 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-2(1)Automated System Account Management
1.00
AC-2(10)Shared and Group Account Credential Change
1.00
AC-2(2)Automated Temporary and Emergency Account Management
1.00
AC-2(3)Disable Accounts
1.00
AC-2(4)Automated Audit Actions
1.00
AC-3Access Enforcement
1.00
AC-3(7)Role-based Access Control
1.00
AC-4Information Flow Enforcement
1.00
AC-6(10)Prohibit Non-privileged Users from Executing Privileged Functions
1.00
AC-6(9)Log Use of Privileged Functions
1.00

+32 more (top 10 by confidence shown)

NIST 800-1710 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.

3.1.3
1.00
CCI1 mapping
CCI-001368
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (4) 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-09
1.00
ID.AM-03
1.00
PR.DS-10
1.00
PR.IR-01
1.00

Who does this work

18 NICE work roles and 10 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-221025r622190_chk)

Review the switch configuration to verify that there are ACLs defined to only accept routes for prefixes that belong to specific customers. Step 1: Verify prefix list has been configured for each customer containing prefixes belonging to each customer as shown in the example below: ip prefix-list PREFIX_FILTER_CUST1 seq 5 permit x.13.1.0/24 le 32 ip prefix-list PREFIX_FILTER_CUST1 seq 10 deny 0.0.0.0/0 ge 8 ip prefix-list PREFIX_FILTER_CUST2 seq 5 permit x.13.2.0/24 le 32 ip prefix-list PREFIX_FILTER_CUST2 seq 10 deny 0.0.0.0/0 ge 8 Step 2: Verify that the prefix lists has been applied to all to the applicable CE peers as shown in the example below: router bgp xx no synchronization bgp log-neighbor-changes neighbor x.12.4.14 remote-as 64514 neighbor x.12.4.14 prefix-list FILTER_PREFIXES_CUST1 in neighbor x.12.4.16 remote-as 64516 neighbor x.12.4.16 prefix-list FILTER_PREFIXES_CUST2 in Note: Routes to PE-CE links within a VPN are needed for troubleshooting end-to-end connectivity across the MPLS/IP backbone. Hence, these prefixes are an exception to this requirement. If the switch is not configured to reject inbound route advertisements from each CE switch for prefixes that are not allocated to that customer, this is a finding.

Fix Text (F-22729r408870_fix)

Configure the switch to reject inbound route advertisements from each CE switch for prefixes that are not allocated to that customer. Step 1: Configure a prefix list for each customer containing prefixes belonging to each. SW1(config)#ip prefix-list PREFIX_FILTER_CUST1 permit x.13.1.0/24 le 32 SW1(config)#ip prefix-list PREFIX_FILTER_CUST1 deny 0.0.0.0/0 ge 8 SW1(config)#ip prefix-list PREFIX_FILTER_CUST2 permit x.13.2.0/24 le 32 SW1(config)#ip prefix-list PREFIX_FILTER_CUST2 deny 0.0.0.0/0 ge 8 Step 2: Apply the prefix list filter inbound to each CE neighbor as shown in the example. SW1(config)#router bgp xx SW1(config-switch)#neighbor x.12.4.14 prefix-list FILTER_PREFIXES_CUST1 in SW1(config-switch)#neighbor x.12.4.16 prefix-list FILTER_PREFIXES_CUST2 in