The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol affects IBM WebSphere MQ Telemetry (MQXR) service.
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
The affected ciphersuite is available via the Telemetry (MQXR) service provided by;
- IBM WebSphere MQ 22.214.171.124 and earlier maintenance
- IBM WebSphere MQ 126.96.36.199 and earlier maintenance
- IBM WebSphere MQ 188.8.131.52 and earlier maintenance
The affected ciphersuites are disabled completely or disabled for small key sizes in the Telemetry MQXR service by default in;
Workarounds and Mitigations
The affected ciphersuites can be disabled in the Telemetry (MQXR) service by restricting the ciphersuites that are used by the Java runtime.
National Security Agency (NSA) Suite B Cryptography
The government of the Unites States of America produces technical advice on IT systems and security, including data encryption. The US National Security Agency (NSA) recommends a set of interoperable cryptographic algorithms in its Suite B standard.
The Suite B standard specifies a mode of operation in which only a specific set of secure cryptographic algorithms are used. The Suite B standard specifies:
- The encryption algorithm (AES)
- The key exchange algorithm (Elliptic Curve Diffie-Hellman, also known as ECDH)
- The digital signature algorithm (Elliptic Curve Digital Signature Algorithm, also known as ECDSA)
- The hashing algorithms (SHA-256 or SHA-384)
Configure the Telemetry (MQXR) service to only accept Suite B cryptographic algorithms by adding the following line to the java.properties file under the ../mqxr/config subdirectory of the IBM WebSphere MQ installation;
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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Reported to IBM by the WeakDH team at https://weakdh.org
4th June 2015: Original version published
19th June 2015: Details of 184.108.40.206 fix added
2nd November 2015: Details of 7.1 and 7.5 ifixes added
*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.
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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15 June 2018