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Security Bulletin: Vulnerability in Diffie-Hellman ciphers may affect IBM Java shipped with IBM Notes and Domino (CVE-2015-4000)

Security Bulletin


Summary

IBM Java is shipped as a component of both IBM Notes and Domino. The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol may affect IBM Java. The IBM Notes and Domino native implementation of TLS 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".

Affected Products and Versions


IBM Notes and Domino 9.0.1 Fix Pack 4 (plus Interim Fix) and earlier
IBM Notes and Domino Domino 8.5.3 Fix Pack 6 (plus Interim Fixes) and earlier
All 9.0 and 8.5.x releases of IBM Notes and Domino prior to those listed above

Remediation/Fixes

Vulnerability in Diffie-Hellman ciphers may affect IBM Java shipped with IBM Notes and Domino (CVE-2015-4000) is also tracked as SPR# KLYH9Y7PWX.

Refer to the JVM tabs in the technotes linked below for download links to a single standalone Java patch that addresses this vulnerability for 9.0.1 Fix Pack 4 (plus Interim Fix), and 8.5.3 Fix Pack 6 (plus Interim Fixes).



Customers on earlier releases may open a Service Request with IBM Support and reference SPR KLYH9Y7PWX for custom fix.

Workarounds and Mitigations

Set https.cipherSuites jvm property to exclude DHE cipher suites. You can add jvm property settings in the following locations:

  • For Notes clients, <Notes Installation>\framework\rcp\deploy\jvm.properties
  • For Domino server, <Domino Installation>\jvm\lib\security\java.security

Example settings:
    vmarg.Dciphers=-Dhttps.cipherSuites=TLS_RSA_WITH_AES_128_CBC_SHA256,TLS_RSA_WITH_AES_128_CBC_SHA,SSL_RSA_WITH_3DES_EDE_CBC_SHA,TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA,TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA,TLS_EMPTY_RENEGOTIATION_INFO_SCSV

    --or--

    https.cipherSuites=https.cipherSuites=TLS_RSA_WITH_AES_128_CBC_SHA256,TLS_RSA_WITH_AES_128_CBC_SHA,SSL_RSA_WITH_3DES_EDE_CBC_SHA,TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA,TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA,TLS_EMPTY_RENEGOTIATION_INFO_SCSV

These settings disable DHE ciphers in HTTPSConnections.

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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References

Off

*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

According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES ""AS IS"" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.

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Document Information

Modified date:
16 June 2018

UID

swg21960614