2017-01 Security Bulletin: Junos: SRX Series denial of service vulnerability in flowd due to crafted multicast packets (CVE-2017-2300)Product Affected:This issue affects any SRX Series Services Gateway chassis cluster
Problem:The flowd daemon on the primary node of an SRX Series chassis cluster may crash and restart when attempting to synchronize a multicast session created via crafted multicast packets.  Upon the flowd crash, data plane redundancy groups will fail over to the secondary node in the chassis cluster while flowd on the primary node restarts.This issue only occurs in chassis cluster configurations that process transit multicast traffic.  Transit multicast traffic is processed on an SRX services gateway by enabling PIM in normal Flow Mode, or via security policies permitting transit multicast traffic in L2/Transparent Mode.Juniper SIRT is not aware of any malicious exploitation of this vulnerability.No other Juniper Networks products or platforms are affected by this issue.This issue has been assigned CVE-2017-2300.
Solution:The following software releases have been updated to resolve this specific issue: Junos OS 12.1X46-D65, 12.3X48-D40, 15.1X49-D60, and all subsequent releases.This issue is being tracked as PR 1188853 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:Disallow transit multicast traffic, or isolate/disable the secondary node of the chassis cluster until an upgrade can be performed.
For SRXs running in Transparent Mode, any security policies permitting transit multicast traffic should be disabled (default policy is deny-all).
For SRXs running in normal Flow Mode, transit multicast traffic can also be stopped by disabling PIM protocol.

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:
2017-01-11: Initial publication2017-01-18: Devices with security policies permitting transit multicast traffic in Transparent Mode are also vulnerable

Related Links:CVSS Score:6.5 (CVSS:3.0/AV:A/AC:L/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 KB 16446 “Common Vulnerability Scoring System (CVSS) and Juniper’s Security Advisories.”

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