STIGQter: STIG Summary: Cisco IOS XE Router RTR Security Technical Implementation Guide Version: 2 Release: 2 Benchmark Date: 23 Apr 2021:

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

DISA Rule

SV-216691r531086_rule

Vulnerability Number

V-216691

Group Title

SRG-NET-000205-RTR-000006

Rule Version

CISC-RT-000530

Severity

CAT II

CCI(s)

• CCI-001097 - The information system monitors and controls communications at the external boundary of the information system and at key internal boundaries within the system.

Weight

10

Fix Recommendation

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.

R1(config)#router bgp xx
R1(config-router)#neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out

Check Contents

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
neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out

If the router is not configured to reject outbound route advertisements for prefixes belonging to the IP core, this is a finding.

Vulnerability Number

V-216691

Documentable

False

Rule Version

CISC-RT-000530

Severity Override Guidance

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
neighbor x.1.4.12 prefix-list FILTER _CORE_PREFIXES out

If the router is not configured to reject outbound route advertisements for prefixes belonging to the IP core, this is a finding.

Check Content Reference

M

Target Key

4028

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