Security Bulletin
Summary
The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol affects IBM® Support Assistant
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 Support Assistant Team Server version 5.0.0, 5.0.1, 5.0.1.1 and 5.0.2
Remediation/Fixes
none
Workarounds and Mitigations
The Logjam attack which affects TLS connections using the Diffie-Hellman (DH) key exchange protocol may affect the IBM Support Assistant. The IBM WebSphere Application Server Liberty shipped with IBM Support Assistant has DH and DHE ciphers included in the "STRONG" or "HIGH", "MEDIUM" and "LOW" cipher lists. They also could be present if you have a "CUSTOM" list of ciphers. You will need to remove any of the ciphers that begin with SSL_* or TLS_* that also have DH or DHE in the Name from your IBM Support Assistant SSL configuration. This does NOT include ciphers that have ECDH or ECDHE in the Name, these are elliptic curve Diffie-Hellman ciphers and they are not affected.
To change the list of enabled ciphers:
1. Open a command prompt, then change directory to the <isa_install>/ISA5/wlp/usr/servers/isa directory.
2. Open the server.xml file with a text editor.
3. Add the enabledCiphers attribute with the list of ciphers.
- See IBM SDK Cipher suites Knowledge Center for more information on the IBM SDK Java Technology Edition ciphers that are supported
- For additional details on how to change the configuration refer to the Liberty Profile: SSL Configuration attributes Knowledge Center
Refer to the Security Bulletin for WebSphere Application Server Liberty Profile for additional details.
You should verify applying this configuration change does not cause any compatibility issues. Not disabling the DH or DHE stream ciphers will expose yourself to the Logjam 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
Acknowledgement
Reported to IBM by The WeakDH team at https://weakdh.org
Change History
10 June 2015: original document 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:
15 June 2018
UID
swg21959500