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2015-10 Security Bulletin: Junos: TCP reassembly denial of service attack (CVE-2014-6449)

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Article ID: JSA10696 SECURITY_ADVISORIES Last Updated: 14 Oct 2015Version: 1.0
Product Affected:
This issue can affect any product or platform running Junos OS.​​
Problem:
Receipt of a very specific sequence of fragmented crafted packets destined to the device ​can lead to consumption of all available buffers and causes a denial of service. Transit traffic cannot trigger this issue, nor is transit traffic affected by the denial of service.

This attack is most effective against short-lived TCP connections.

Exploitation against TCP-based routing protocol ports such as BGP is significantly more complex due to the nature and timing required by the attack.

This issue was found during internal product security testing.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue is assigned CVE-2014-6449.
Solution:
The following software releases have been updated to resolve this specific issue: Junos OS 12.1X44-D50, 12.1X46-D35, 12.1X47-D25, 12.3R10, 12.3X48-D15, 13.2R8, 13.3R7, 14.1R5, 14.2R1, and all subsequent releases.

This issue is being tracked as PR 985940 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:
Use access lists or firewall filters to limit access to the device via TCP only from trusted hosts.

In most cases, it is safe to apply packet filters which will prevent fragmented packets from arriving on the router. Usually, fragmented packets received by a router indicate a problem with the network or a DoS attack against the router. In either case, fragmented packets should be dropped to protect the router's control and management plane.

In addition to the recommendation listed above, it is good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the router via TCP only from trusted, administrative networks or hosts.



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:
Modification History:

2015-10-14: Initial publication

CVSS Score:
5.3 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Severity Level:
Medium
Severity 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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