Check: CISC-RT-000840
Cisco IOS XE Router RTR STIG:
CISC-RT-000840
(in versions v2 r9 through v1 r1)
Title
The Cisco multicast Rendezvous Point (RP) router must be configured to filter Protocol Independent Multicast (PIM) Join messages received from the Designated Router (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 router 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: R2(config)#ip access-list standard PIM_JOIN_FILTER R2(config-std-nacl)#deny 239.8.0.0 0.0.255.255 R2(config-std-nacl)#permit any R2(config-std-nacl)#exit R2(config)#ip pim accept-rp 10.2.2.2 PIM_JOIN_FILTER R2(config)#end
Additional Identifiers
Rule ID: SV-216722r531086_rule
Vulnerability ID: V-216722
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 |