The Juniper 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.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-253995	JUEX-RT-000230	SV-253995r844018_rule		Low

Description

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.

STIG	Date
Juniper EX Series Switches Router Security Technical Implementation Guide	2024-06-10

Details

Check Text (C-57447r844016_chk)

Verify that the RP router is configured to filter PIM register messages.
[edit policy-options]
policy-statement <name> {
term filter_groups {
from {
route-filter <multicast address>/<mask> orlonger;
route-filter <multicast address>/<mask> exact;
<additional groups to filter>
}
then reject;
}
term filter_sources {
from {
source-address-filter <source host address>/32 exact;
source-address-filter <source subnet address>/<mask> orlonger;
<additional source addresses to filter>
}
then reject;
}
term accept_others {
then accept;
}
}
[edit protocols]
pim {
mode sparse;
import <policy name>;
}

Note: Alternative is to verify all designated routers are filtering IGMP Membership Report (a.k.a., join) messages received from hosts.

If the RP router peering with PIM-SM routers is not configured with a PIM import policy to block registration messages for any undesirable multicast groups and Bogon sources, this is a finding.

Fix Text (F-57398r844017_fix)

RP routers that are peering with customer PIM-SM routers must implement a PIM import policy to block join messages for reserved and any undesirable multicast groups.

set policy-options policy-statement <name> term filter_groups from route-filter <multicast address>/<mask> <match criterion>
set policy-options policy-statement <name> term filter_groups from route-filter <additional multicast address>/<mask> <match criterion>
set policy-options policy-statement <name> term filter_groups then reject

set policy-options policy-statement <name> term filter_source from source-address-filter <source address>/<mask> <match criterion>
set policy-options policy-statement <name> term filter_source from source-address-filter <additional source address>/<mask> <match criterion>
set policy-options policy-statement <name> term filter_source then reject

set policy-options policy-statement <name> term accept_others then accept

set protocols pim import <policy name>