Security Bulletin: Vulnerability with Diffie-Hellman ciphers may affect WebSphere Lombardi Edition and IBM Business Process Manager (CVE-2015-4000)

Security Bulletin

Summary

The LogJam Attack on Diffie-Hellman ciphers (CVE-2015-4000) may affect some configurations of IBM WebSphere Application Server Full Profile and IBM WebSphere Application Server Liberty Profile that are shipped as a component of WebSphere Lombardi Edition and IBM Business Process Manager. The IBM HTTP Server used by WebSphere Application Server is not affected.

Vulnerability Details

CVEID: CVE-2015-4000
DESCRIPTION: The TLS protocol could allow a remote attacker to obtain sensitive information, caused by the failure to properly convey a DHE_EXPORT ciphersuite choice. An attacker could exploit this vulnerability using man-in-the-middle techniques to force a downgrade to 512-bit export-grade cipher. Successful exploitation could allow an attacker to recover the session key as well as modify the contents of the traffic. This vulnerability is commonly referred to as "Logjam".
CVSS Base Score: 4.3
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/103294 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:M/Au:N/C:P/I:N/A:N)

Affected Products and Versions

IBM Business Process Manager V7.5.x through V8.5.6.0
WebSphere Lombardi Edition V7.2.0.x

For earlier unsupported versions of the products, IBM recommends upgrading to a fixed, supported version of the product.

Remediation/Fixes

Please consult the security bulletin Security Bulletin: Vulnerability with Diffie-Hellman ciphers may affect IBM WebSphere Application Server (CVE-2015-4000) for vulnerability details and information about fixes.
The following setting in java.secruity allows you to reenable ciphers using DH and DHE key exchange that you had to disable as a temporary workaround:
jdk.tls.disabledAlgorithms=SSLv3, RC4, DH keySize <768

Workarounds and Mitigations

None

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Important Note

IBM strongly suggests that all System z customers be subscribed to the System z Security Portal to receive the latest critical System z security and integrity service. If you are not subscribed, see the instructions on the System z Security web site. Security and integrity APARs and associated fixes will be posted to this portal. IBM suggests reviewing the CVSS scores and applying all security or integrity fixes as soon as possible to minimize any potential risk.

References

Complete CVSS v2 Guide
On-line Calculator v2

Off

Acknowledgement

Reported to IBM by The WeakDH team at https://weakdh.org

Change History

2015-06-03: Original Version Published
2015-06-26: explaining new Java setting replacing the workaround

*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.

Disclaimer

Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.

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Tips

Security Bulletin: Vulnerability with Diffie-Hellman ciphers may affect WebSphere Lombardi Edition and IBM Business Process Manager (CVE-2015-4000)