Security Bulletin: Vulnerability in IBM Java SDK affects Rational Developer for System z (CVE-2015-7575)

Summary

There is a vulnerability in IBM® SDK Java™ Technology Edition that is used by Rational Developer for System z. This vulnerability, commonly referred to as “SLOTH”, was disclosed as part of the IBM Java SDK updates in January 2016.

Vulnerability Details

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CVEID: CVE-2015-7575**
DESCRIPTION:** The TLS protocol could allow weaker than expected security caused by a collision attack when using the MD5 hash function for signing a ServerKeyExchange message during a TLS handshake. An attacker could exploit this vulnerability using man-in-the-middle techniques to impersonate a TLS server and obtain credentials. This vulnerability is commonly referred to as “SLOTH”.
CVSS Base Score: 7.1
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/109415 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/UI:U/C:H/I:L/A:N)

Affected Products and Versions

Principal Product and Version(s)

• Rational Developer for System z, versions 8.5.1.6 and earlier
• Rational Developer for System z, versions 9.0.1.4 and earlier
• Rational Developer for System z, versions 9.1.1.2 and earlier
• Rational Developer for z Systems, versions 9.5.1 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 7 for 8.5.x
• Rational Developer for System z Interim Fix 7 for 9.0.x
• Rational Developer for System z Interim Fix 7 for 9.1.x
• Rational Developer for System z Interim Fix 2 for 9.5.x

Workarounds and Mitigations

Users of Java 7 and later can address the issue by updating the /jre/lib/security/java.security file as follows (both steps are required):

· Add MD5 to the jdk.certpath.disabledAlgorithms property - e.g. jdk.certpath.disabledAlgorithms=MD2, RSA keySize < 1024, MD5

· Add MD5withRSA to the jdk.tls.disabledAlgorithms property - e.g. jdk.tls.disabledAlgorithms=SSLv3, RC4, DH keySize < 768, MD5withRSA

Java 6 requires code changes in the JSSE component in addition to the java.security file modifications, so upgrading the JDK is the only solution.