Security Bulletin: Vulnerabilities in OpenSSL including Logjam affect Rational Developer for System z (CVE-2015-4000)

Summary

OpenSSL vulnerabilities were disclosed by the OpenSSL Project and affect Rational Developer for System z. This includes the Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol (CVE-2015-4000). Rational Developer for System z has addressed the applicable CVEs.

Vulnerability Details

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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

Principal Product and Version(s)

| Affected Supporting Product and Version
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Rational Developer for System z, versions 8.5.x, 9.0.x, 9.1.x|

• IBM SDK, Java Technology Edition, Version 7 Service Refresh 9 and earlier

• Remediation/Fixes

IBM has provided patches for all affected versions.

Follow the installation instructions in the README files included with the patch.

The fix can be obtained at the following locations:

• Rational Developer for System z Interim Fix 5 for 8.5.x
• Rational Developer for System z Interim Fix 5 for 9.0.x
• Rational Developer for System z Interim Fix 5 for 9.1.x
• As the length of the server key size are increased, the amount of CPU required for full TLS/SSL handshake can significantly increase. Please carefully test and assess the impact to your CPU requirements to ensure sufficient CPU resources, otherwise the system availability may be impacted.

You should verify applying this configuration change does not cause any compatibility issues. If you change the default setting after applying the fix, you will expose yourself to the attack described above. IBM recommends that you review your entire environment to identify other areas where you have enabled the Diffie-Hellman key-exchange protocol used in TLS and take appropriate mitigation and remediation actions.