Security Bulletin
Summary
The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol affects IBM i.
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
Releases V5R3, V5R4, 6.1, 7.1 and 7.2 of IBM i are affected.
Remediation/Fixes
The issue can be fixed by applying a PTF to the IBM i Operating System.
Releases 6.1, 7.1 and 7.2 of IBM i are supported and will be fixed. Releases V5R3 and V5R4 are unsupported and will not be fixed.
The IBM i OS PTF numbers are:
Release 6.1 – SI57527
Release 7.1 – SI57473
Release 7.2 – SI57468
PTFs for IBM i Java
Java60
-----------------------
6.1 and 7.1
32bit: SI57243
64bit: SI57246
7.2
32bit: SI57244
64bit: SI57245
Java626
-----------------------
6.1 and 7.1
32bit: SI57250
64bit: SI57247
7.2
32bit: SI57248
64bit: SI57249
Java70
-----------------------
6.1 and 7.1
32bit: SI57278 SI57277
64bit: SI57279 SI57280
7.2
32bit: SI57281
64bit: SI57282
Java 71
-----------------------
7.1
32bit: SI57291
64bit: SI57293
7.2
32bit: SI57292
64bit: SI57294
Java80
-----------------------
7.1
32bit: SI57296
64bit: SI57298
7.2
32bit: SI57297
64bit: SI57299
For CVE-2015-4000: As the length of the server key size are increased, the amount of CPU required for full TLS/SSL handshake can significantly increase. Please carefully test and assess the impact to your CPU requirements to ensure sufficient CPU resources, otherwise the system availability may be impacted.
For CVE-2015-4000: 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.
Important note: IBM recommends that all users running unsupported versions of affected products upgrade to supported and fixed version of affected products.
Workarounds and Mitigations
None known
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References
*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:
18 December 2019
UID
nas8N1020841