STIGQter: STIG Summary: Cisco NX-OS Switch RTR Security Technical Implementation Guide Version: 2 Release: 1 Benchmark Date: 23 Apr 2021:

The Cisco multicast Designated switch (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join a multicast group only from sources that have been approved by the organization.

DISA Rule

SV-221139r622190_rule

Vulnerability Number

V-221139

Group Title

SRG-NET-000364-RTR-000115

Rule Version

CISC-RT-000870

Severity

CAT II

CCI(s)

• CCI-002403 - The information system only allows incoming communications from organization-defined authorized sources routed to organization-defined authorized destinations.

Weight

10

Fix Recommendation

Step 1: Configure the report policy to filter IGMP Membership Report messages as shown in the example below:

SW1(config-route-map)# route-map ALLOWED_SOURCES permit 10
SW1(config-route-map)# match ip multicast source x.1.2.6/32
SW1(config-route-map)# route-map ALLOWED_SOURCES permit 20
SW1(config-route-map)# match ip multicast source x.1.2.7/32
SW1(config-route-map)# route-map ALLOWED_SOURCES deny 30
SW1(config-route-map)# match ip multicast source 0.0.0.0/0
SW1(config-route-map)# exit

Step 2: Apply the report policy to all applicable interfaces.

SW1(config)# int e2/4
SW1(config-if)# ip igmp report-policy ALLOWED_SOURCES
SW1(config-if)# end

Check Contents

Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to only join multicast groups from sources that have been approved.

Step 1: Verify that all host-facing interfaces are configured to filter IGMP Membership Report messages (IGMP joins) as shown in the example below:

interface Ethernet2/4
no switchport
ip address 10.2.22.3/24
ip pim sparse-mode
ip igmp version 3
ip igmp report-policy ALLOWED_SOURCES

Step 2: Verify that the report policy permits only sources that have been approved by the organization.

route-map ALLOWED_SOURCES permit 10
match ip multicast source x.1.2.6/32
route-map ALLOWED_SOURCES permit 20
match ip multicast source x.1.2.7/32
route-map ALLOWED_SOURCES deny 30
match ip multicast source 0.0.0.0/0

Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation.

If the DR is not filtering IGMP or MLD report messages, this is a finding.

Vulnerability Number

V-221139

Documentable

False

Rule Version

CISC-RT-000870

Severity Override Guidance

Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to only join multicast groups from sources that have been approved.

Step 1: Verify that all host-facing interfaces are configured to filter IGMP Membership Report messages (IGMP joins) as shown in the example below:

interface Ethernet2/4
no switchport
ip address 10.2.22.3/24
ip pim sparse-mode
ip igmp version 3
ip igmp report-policy ALLOWED_SOURCES

Step 2: Verify that the report policy permits only sources that have been approved by the organization.

route-map ALLOWED_SOURCES permit 10
match ip multicast source x.1.2.6/32
route-map ALLOWED_SOURCES permit 20
match ip multicast source x.1.2.7/32
route-map ALLOWED_SOURCES deny 30
match ip multicast source 0.0.0.0/0

Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation.

If the DR is not filtering IGMP or MLD report messages, this is a finding.

Check Content Reference

M

Target Key

4075

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