STIGQter: STIG Summary: Cisco IOS XR Router RTR Security Technical Implementation Guide Version: 2 Release: 1 Benchmark Date: 23 Oct 2020:

The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to filter source-active multicast advertisements to external MSDP peers to avoid global visibility of local-only multicast sources and groups.

DISA Rule

SV-216821r531087_rule

Vulnerability Number

V-216821

Group Title

SRG-NET-000018-RTR-000008

Rule Version

CISC-RT-000930

Severity

CAT III

CCI(s)

• CCI-001368 - The information system enforces approved authorizations for controlling the flow of information within the system based on organization-defined information flow control policies.

Weight

10

Fix Recommendation

Configure the router with an export policy to avoid global visibility of local multicast (S, G) states. The example below will prevent exporting multicast active sources belonging to the private network.

RP/0/0/CPU0:R2(config)#ipv4 access-list OUTBOUND_MSDP_SA_FILTER
RP/0/0/CPU0:R2(config-ipv4-acl)#deny ipv4 10.0.0.0 0.255.255.255 any
RP/0/0/CPU0:R2(config-ipv4-acl)#permit ip any any
RP/0/0/CPU0:R2(config-ipv4-acl)#exit
RP/0/0/CPU0:R2(config)#router msdp
RP/0/0/CPU0:R2(config-msdp)#sa-filter out list OUTBOUND_MSDP_SA_FILTER
RP/0/0/CPU0:R2(config-msdp)#end

Check Contents

Review the router configuration to determine if there is export policy to block local source-active multicast advertisements.

Step 1: Verify that an outbound source-active filter is bound to each MSDP peer as shown in the example below.

router msdp
sa-filter in list INBOUND_MSDP_SA_FILTER
sa-filter out list OUTBOUND_MSDP_SA_FILTER

Step 2: Review the access lists referenced by the source-active filters and verify that MSDP source-active messages being sent to MSDP peers do not leak advertisements that are local.

ipv4 access-list OUTBOUND_MSDP_SA_FILTER
10 deny ipv4 10.0.0.0 0.255.255.255 any
20 permit ipv4 any any

If the router is not configured with an export policy to filter local source-active multicast advertisements, this is a finding.

Vulnerability Number

V-216821

Documentable

False

Rule Version

CISC-RT-000930

Severity Override Guidance

Review the router configuration to determine if there is export policy to block local source-active multicast advertisements.

Step 1: Verify that an outbound source-active filter is bound to each MSDP peer as shown in the example below.

router msdp
sa-filter in list INBOUND_MSDP_SA_FILTER
sa-filter out list OUTBOUND_MSDP_SA_FILTER

Step 2: Review the access lists referenced by the source-active filters and verify that MSDP source-active messages being sent to MSDP peers do not leak advertisements that are local.

ipv4 access-list OUTBOUND_MSDP_SA_FILTER
10 deny ipv4 10.0.0.0 0.255.255.255 any
20 permit ipv4 any any

If the router is not configured with an export policy to filter local source-active multicast advertisements, this is a finding.

Check Content Reference

M

Target Key

4029

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