Security Bulletin
Summary
The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol affects PowerKVM.
Vulnerability Details
CVE Information: (copy/paste-able; will update after page submission. Provided by system to make it easy to cut and paste data.)
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".
See https://weakdh.org/ for ongoing analysis and remediation recommendations.
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)
Remediation/Fixes
Fix is made available via Fix Central (https://ibm.biz/BdEnT8) in 2.1.1 build 55 and all later builds and fix packs. For systems currently running fix levels of PowerKVM prior to 2.1.1, please see http://download4.boulder.ibm.com/sar/CMA/OSA/05e4c/0/README for prerequisite fixes and instructions. Customers can also update from 2.1.1 (GA and later levels) by using "yum update".
In addition the code patches provided, IBM urges its customers to ensure that crypto-related configuration files on PowerKVM servers are set to reflect best practices. On PowerKVM, this includes the nginx configuration files in /etc/nginz and the related nginx-based kimchi configuration in /etc/kimchi
Workarounds and Mitigations
See the recommendations for mitigation by configuration at https://weakdh.org/sysadmin.html
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References
Change History
17 June 2015 - Initial Version
*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:
17 June 2018
UID
isg3T1022395