When High-End SRX-Series chassis have policies with one or more ALG’s (application layer gateways) enabled, which are applied to in-transit traffic, this may trigger a number of failure conditions which could cause various types of denials of service to traffic in-transit.

Continued in-transit traffic matching ALG rules can create a sustained denial of service.

This issue affects both standalone or cluster mode configurations with different denial of service permutations.

Standalone:

• In standalone HE chassis deployments, existing sessions will function normally, new session establishment due to high CP utilization may cause new sessions to not establish.

• In cluster HE chassis deployments, the fab link between chassis may be unable to sustain communication causing the backup to go ineligible due to fab link failure.
• New sessions setups due to high CP utilization may be unable to be established.
• The primary chassis processing LACP communication may lose LACP links triggering failover conditions which could create sustained flip-flop failovers between each chassis, including possible line card reboots, leading to long term denials of service.

The following software releases have been updated to resolve this specific issue: Junos OS 12.1X46-D50, 12.1X47-D23, 12.1X47-D35, 12.3X48-D25, 15.1X49-D40 and subsequent releases.

This issue is being tracked as PR 1150971 and is visible on the Customer Support website.

KB16765 [juniper.net] - "In which releases are vulnerabilities fixed?" describes which release vulnerabilities are fixed as per our End of Engineering and End of Life support policies.

The following workarounds may be used to mitigate, reduce or resolve the risk of the problem from occuring:

• Disabling all ALG's will mitigate the issue until such time that an upgrade can be performed on the chassis.
• Breaking cluster nodes if present and operating standalone High End SRX-Series Service Gateways in parallel while also distributing traffic equally between both standalone devices may reduce the number of high CP utilization on each chassis and may mitigate the risk of line card reboots.

2016-07-13: Initial publication
2016-07-22: Added language that any and all ALG's are impacted by this JSA.

• KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories." [juniper.net]
• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2016-1276 Junos OS: On High-End SRX-Series, ALG’s applied to in-transit traffic may trigger high CP (central point) utilization leading to denial of services.
• KB16446: [SRX/J-series] Default status of ALGs [juniper.net]