STIGQter 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 only multicast groups that have been approved by the organization.

DISA Rule

SV-221138r622190_rule

Vulnerability Number

V-221138

Group Title

SRG-NET-000364-RTR-000114

Rule Version

CISC-RT-000860

Severity

CAT III

CCI(s)

Weight

10

Fix Recommendation

Configure the DR to filter the IGMP or MLD Membership Report messages to allow hosts to join only those multicast groups that have been approved.

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

SW1(config)# route-map ALLOWED_GROUPS permit
SW1(config-route-map)# match ip multicast group 233.1.1.0/24
SW1(config-route-map)# route-map ALLOWED_GROUPS permit 20
SW1(config-route-map)# match ip multicast group 233.1.1.0/32
SW1(config-route-map)# route-map ALLOWED_GROUPS permit 30
SW1(config-route-map)# match ip multicast group 233.1.1.1/32
SW1(config-route-map)# route-map ALLOWED_GROUPS deny 40
SW1(config-route-map)# match ip multicast group 224.0.0.0/4
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_GROUPS
SW1(config-if)# end

Check Contents

Review the configuration of the DR to verify that it is filtering IGMP or MLD Membership Report messages, allowing hosts to join only those groups 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_GROUPS

Step 2: Verify that the report policy denies unauthorized groups or permits only authorized groups.

route-map ALLOWED_GROUPS permit 10
match ip multicast group 233.1.1.0/24
route-map ALLOWED_GROUPS permit 20
match ip multicast group 233.1.1.0/32
route-map ALLOWED_GROUPS permit 30
match ip multicast group 233.1.1.1/32
route-map ALLOWED_GROUPS deny 40
match ip multicast group 224.0.0.0/4

Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. This requirement is not applicable to Any Source Multicast (ASM) since the filtering is being performed by the Rendezvous Point.

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

Vulnerability Number

V-221138

Documentable

False

Rule Version

CISC-RT-000860

Severity Override Guidance

Review the configuration of the DR to verify that it is filtering IGMP or MLD Membership Report messages, allowing hosts to join only those groups 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_GROUPS

Step 2: Verify that the report policy denies unauthorized groups or permits only authorized groups.

route-map ALLOWED_GROUPS permit 10
match ip multicast group 233.1.1.0/24
route-map ALLOWED_GROUPS permit 20
match ip multicast group 233.1.1.0/32
route-map ALLOWED_GROUPS permit 30
match ip multicast group 233.1.1.1/32
route-map ALLOWED_GROUPS deny 40
match ip multicast group 224.0.0.0/4

Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. This requirement is not applicable to Any Source Multicast (ASM) since the filtering is being performed by the Rendezvous Point.

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

Check Content Reference

M

Target Key

4075

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