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

Created by Guirlyn V Olivar on
Published URL:
https://www.ibm.com/support/pages/node/533143
533143

Security Bulletin


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
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:

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.

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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

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Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

Change History

24 July 2015: Update published

*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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Document Information

Modified date:
27 October 2020

UID

swg21962844

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