Security Bulletin: Vulnerability in Diffie-Hellman ciphers affects IBM Virtualization Engine TS7700 (CVE-2015-4000)

Summary

The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol affects IBM Virtualization Engine TS7700.

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

All versions of microcode for the IBM Virtualization Engine TS7700 (3957-V06, 3957-V07, 3957-VEA, 3957-VEB) prior to release R2.1 are affected. In addition, microcode versions of releases R2.1, R3.0, R3.1 and R3.2 prior to and including the following are also affected:

Release

| Version
—|—
R3.2| 8.32.1.8
R3.1| 8.31.0.92
R3.0| 8.30.3.4
R2.1| 8.21.0.178

Remediation/Fixes

Contact IBM Service at 1-800-IBM-SERV to arrange an upgrade to the latest microcode level followed by the installation of vtd_exec.213, vtd_exec.214 and vtd_exec.215 as needed. Minimum microcode levels are shown below:

Release

| Fix
—|—
R3.0, R3.1 or R3.2| Upgrade to 8.32.1.8 or later + vtd_exec.213 + vtd_exec.214 + vtd_exec.215
R2.1| Upgrade to 8.21.0.178 or later + vtd_exec.213 + vtd_exec.214 + vtd_exec.215
Older Releases| Upgrade to 8.21.0.178 or later + vtd_exec.213 + vtd_exec.214 + vtd_exec.215

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.

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.

Workarounds and Mitigations

Although IBM recommends that you upgrade to the fixes identified above, you can mitigate, but not eliminate the risk of these vulnerabilities by restricting physical and network access to the TS7700 to authorized users and IBM Service Personnel only.