Check: CISC-RT-000840
Cisco IOS XE Switch RTR STIG:
CISC-RT-000840
(in versions v2 r5 through v1 r0.1)
Title
The Cisco multicast Rendezvous Point (RP) switch must be configured to filter Protocol Independent Multicast (PIM) Join messages received from the Designated Cisco switch (DR) for any undesirable multicast groups. (Cat III impact)
Discussion
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 join messages are only accepted for authorized multicast groups.
Check Content
Verify that the RP is configured to filter PIM join messages for any undesirable multicast groups. In the example below, groups from 239.8.0.0/16 are not allowed. ip pim rp-address 10.2.2.2 ip pim accept-rp 10.2.2.2 FILTER_PIM_JOINS … … … ip access-list standard FILTER_PIM_JOINS deny 239.8.0.0 0.0.255.255 permit any ! If the RP is not configured to filter join messages received from the DR for any undesirable multicast groups, this is a finding.
Fix Text
Configure the RP to filter PIM join messages for any undesirable multicast groups as shown in the example below: SW2(config)#ip access-list standard PIM_JOIN_FILTER SW2(config-std-nacl)#deny 239.8.0.0 0.0.255.255 SW2(config-std-nacl)#permit any SW2(config-std-nacl)#exit SW2(config)#ip pim accept-rp 10.2.2.2 PIM_JOIN_FILTER SW2(config)#end
Additional Identifiers
Rule ID: SV-221058r622190_rule
Vulnerability ID: V-221058
Group Title: SRG-NET-000019-RTR-000014
Expert Comments
CCIs
Number | Definition |
---|---|
CCI-001414 |
The information system enforces approved authorizations for controlling the flow of information between interconnected systems based on organization-defined information flow control policies. |
Controls
Number | Title |
---|---|
AC-4 |
Information Flow Enforcement |