Finding ID | Version | Rule ID | IA Controls | Severity |
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V-221057 | CISC-RT-000830 | SV-221057r622190_rule | Low |
Description |
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Real-time multicast traffic can entail multiple large flows of data. An attacker can flood a network segment with multicast packets, over-using the available bandwidth and thereby creating a denial-of-service (DoS) condition. Hence, it is imperative that register messages are accepted only for authorized multicast groups and sources. |
STIG | Date |
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Cisco IOS XE Switch RTR Security Technical Implementation Guide | 2023-02-28 |
Check Text ( C-22772r408965_chk ) |
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Verify that the RP is configured to filter PIM register messages. The example below will deny any multicast streams for groups 239.5.0.0/16 and allow from only sources x.1.2.6 and x.1.2.7. ip pim rp-address 10.1.12.3 ip pim accept-register list PIM_REGISTER_FILTER … … … ip access-list extended PIM_REGISTER_FILTER deny ip any 239.5.0.0 0.0.255.255 permit ip host x.1.2.6 any permit ip host x.1.2.7 any deny ip any any If the RP switch peering with PIM-SM switches is not configured with a policy to block registration messages for any undesirable multicast groups and sources, this is a finding. |
Fix Text (F-22761r408966_fix) |
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Configure the switch to filter PIM register messages received from a multicast DR for any undesirable multicast groups and sources. The example below will deny any multicast streams for groups 239.5.0.0/16 and allow from only sources x.1.2.6 and x.1.2.7. SW2(config)#ip access-list extended PIM_REGISTER_FILTER SW2(config-ext-nacl)#deny ip any 239.5.0.0 0.0.255.255 SW2(config-ext-nacl)#permit ip host x.1.2.6 any SW2(config-ext-nacl)#permit ip host x.1.2.7 any SW2(config-ext-nacl)#deny ip any any SW2(config-ext-nacl)#exit SW2(config)#ip pim accept-register list PIM_REGISTER_FILTER SW2(config)#end |