2015-10 Security Bulletin: Junos: Trio Chipset (Trinity) Denial of service due to maliciously crafted uBFD packet. (CVE-2015-7748)

Product Affected:Any chassis with Trio (Trinity) chipset line cards: MX-Series, EX 9200, TXP with T-4000 Trio (Trinity) chipset line cards, T-4000.

Problem:A remote attacker can cause a denial of service to the Trio Chipset (Trinity) MPC due to maliciously crafted uBFD packets that are received directly, via VPN, MPLS, multicast, broadcast, on vt-interfaces, or otherwise.This issue affects both IPv4 and IPv6 traffic in both ethernet, and non-ethernet physical environments, such as ATM, or SONET, where the crafted packet is received over physical interfaces.If processed from a DPC through to the MPC then in-transit traffic will not be susceptible.In 6PE scenario, if the system is not using LSI/vt then not susceptible.If processed via MPC line card will be affected, the MPC line card will crash.If processed via endpoint receiving MPC line card terminating tunneling protocols such as MPLS/IPSec VPN’s, etc. will be affected, this is considered in-transit traffic scenario.This crash can happen when the crafted packet is directed directly to the lo0 interface IP/physical interface IP/broadcast IPv4 / IPv6 address of the Physical interfaceThis issue is assigned CVE-2015-7748.

Solution:This issue does not apply to Junos OS 13.2 or lower.The following software releases have been updated to resolve this specific issue: Junos OS 13.3R8, 14.1R6, 14.2R5, 15.1R2, 15.1F3, and all subsequent releases.This issue is being tracked as PR 1102581 and is visible on the Customer Support website. KB16765 – “In which releases are vulnerabilities fixed?” describes which release vulnerabilities are fixed as per our End of Engineering and End of Life support policies.​

Workaround:A workaround to apply a control plane (lo0) filter to drop uBFD packets in a layered defense approach may be implemented.For IPv4 packets the following filter may be applied to lo0 interfaces:
family inet {
filter ubfd {
term 1 {
from {
protocol udp;
destination-port 6784;
}
then {
discard;
}
}
term 2 {
then accept;
}
}
}For IPv6 packets the following filter may be applied to lo0 interfaces:
family inet6 {
filter ufbd-v6 {
term 1 {
from {
next-header udp;
destination-port 6784;
}
then {
count ufdb-v6;
discard;
}
}
term 2 {
then accept;
}
}
}

Implementation:How to obtain fixed software: Security vulnerabilities in Junos are fixed in the next available Maintenance Release of each supported Junos version. In some cases, a Maintenance Release is not planned to be available in an appropriate time-frame. For these cases, Service Releases are made available in order to be more timely. Security Advisory and Security Notices will indicate which Maintenance and Service Releases contain fixes for the issues described. Upon request to JTAC, customers will be provided download instructions for a Service Release. Although Juniper does not provide formal Release Note documentation for a Service Release, a list of “PRs fixed” can be provided on request.Modification History: 2015-10-14: Initial publication

Related Links: CVSS Score:5.9 (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

Risk Level:Medium

Risk Assessment:Information for how Juniper Networks uses CVSS can be found at KB16446 “Common Vulnerability Scoring System (CVSS) and Juniper’s Security Advisories”

Acknowledgements:

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