IBM Support

Security Bulletin: TLS padding vulnerability affects Communications Server for Data Center Deployment, Communications Server for AIX, Communications Server for Linux, and Communications Server for Linux on System z (CVE-2014-8730)

Created by Edward Burr on
Published URL:
https://www.ibm.com/support/pages/node/522309
522309

Security Bulletin


Summary

Transport Layer Security (TLS) padding vulnerability via a POODLE (Padding Oracle On Downgraded Legacy Encryption) like attack affects Communications Server for Data Center Deployment, Communications Server for AIX, Communications Server for Linux, and Communications Server for Linux on System z.

Vulnerability Details

CVE-ID: CVE-2014-8730

DESCRIPTION:

Product allows a remote attacker to obtain sensitive information, caused by the failure to check the contents of the padding bytes when using CBC cipher suites of some TLS implementations. A remote user with the ability to conduct a man-in-the-middle attack can use this vulnerability via a POODLE (Padding Oracle On Downgraded Legacy Encryption) like attack to decrypt sensitive information and calculate the plain text of secure connections.

CVSS Base Score: 4.3
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/99216 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

Communications Server for Data Center Deployment, V7
Communications Server for AIX, V6
Communications Server for Linux, V6
Communications Server for Linux on System z, V6

Remediation/Fixes

None

Workarounds and Mitigations

Upgrade GSKit to level 8.0.14.25 or higher, 8.0.15.7 or higher, 8.0.50.0 or higher AND enable the strict enforcement of padding as described below. Communications Server level 6.4.0.3 or higher is required for support of GSKit V8.

On AIX, check GSKit level with commands:
lslpp -L GSKit8.gskcrypt32.ppc.rte
lslpp -L GSKit8.gskssl32.ppc.rte

On Linux on x86, x86_64, or ppc, check GSKit level with commands:
rpm -q gskssl32
rpm -q gskcrypt32

On Linux on System z, check GSKit level with commands:
rpm -q gskssl31
rpm -q gskcrypt31

To upgrade to a required GSKit level, obtain the appropriate product full media refresh as below:
Communications Server for Data Center Deployment (any level)
Communications Server for AIX (6.4.0.5 or higher)
Communications Server for Linux (6.4.0.5 or higher)
Communications Server for Linux on System z (6.4.0.5 or higher)

To enable the strict enforcement of padding, edit or create a file named "environment" in (AIX) /etc/sna or (Linux) /etc/opt/ibm/sna and add the following line in it:


export GSK_STRICTCHECK_CBCPADBYTES=GSK_TRUE
Then stop and restart Communications Server.
This change will persist through future maintenance updates.

Note: This might cause interoperability issues with client software if that software does not perform padding correctly.

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References

Complete CVSS v2 Guide
On-line Calculator v2

Complete CVSS v3 Guide
On-line Calculator v3

Off

Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

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Change History

18 December 2014 Original Version 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

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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Product Synonym

csdcd csaix cslinux commserver comm server sna aixsna

Document Information

Modified date:
03 August 2018

UID

swg21693005

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