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AUSCERT External Security Bulletin Redistribution
ESB-2015.1432
Security Bulletin: Vulnerability with Diffie-Hellman ciphers may affect IBM
WebSphere Application Server (CVE-2015-4000)
2 June 2015
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AusCERT Security Bulletin Summary
---------------------------------
Product: IBM WebSphere Application Server
Publisher: IBM
Operating System: AIX
HP-UX
IBM i
Linux variants
Solaris
Windows
z/OS
Impact/Access: Access Privileged Data -- Remote/Unauthenticated
Provide Misleading Information -- Remote/Unauthenticated
Resolution: Mitigation
CVE Names: CVE-2015-4000
Reference: ESB-2015.1425
Original Bulletin:
http://www-01.ibm.com/support/docview.wss?uid=swg21957980
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Security Bulletin: Vulnerability with Diffie-Hellman ciphers may affect IBM
WebSphere Application Server (CVE-2015-4000)
Security Bulletin
Document information
More support for:
WebSphere Application Server
Security
Software version:
6.1, 7.0, 8.0, 8.5, 8.5.5
Operating system(s):
AIX, HP-UX, IBM i, Linux, Solaris, Windows, z/OS
Software edition:
Base, Developer, Enterprise, Liberty, Network Deployment
Reference #:
1957980
Modified date:
2015-06-01
Summary
The LogJam Attack on Diffie-Hellman ciphers (CVE-2015-4000) may affect some
configurations of IBM WebSphere Application Server Full Profile, IBM WebSphere
Application Server Liberty Profile, and IBM WebSphere Application Server
Hypervisor Edition. The IBM HTTP Server used by WebSphere Application Server
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".
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 following IBM WebSphere Application Server Versions may be affected:
Version 8.5 and 8.5.5 Full Profile and Liberty Profile
Version 8
Version 7
Version 6.1
Remediation/Fixes
None
Workarounds and Mitigations
The Logjam attack which affects TLS connections using the Diffie-Hellman (DH)
key exchange protocol may affect some configurations in WebSphere Application
Server. WebSphere Application Server 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 WebSphere Application Server 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.
Outbound connections from WebSphere Application Server are impacted but
inbound connections are not.
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.
Get Notified about Future Security Bulletins
Subscribe to My Notifications to be notified of important product support
alerts like this.
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 Guide
On-line Calculator V2
Related information
IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog
Acknowledgement
Reported to IBM by The WeakDH team at https://weakdh.org
Change History
01 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
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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