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Cisco WebEx Player WRF File Integer Overflow Vulnerability

04.04.12

BACKGROUND

WebEx Player is used to play recorded WebEx meetings in the '.wrf' file format. More information is available at http://www.webex.com/play-webex-recording.html.

DESCRIPTION

Remote exploitation of an integer overflow vulnerability in Cisco Systems Inc.'s WebEx Player could allow an attacker to execute arbitrary code with the privileges of the current user. It is a standalone product; however, the library used to play the file is also present in the components downloaded by the ActiveX control version of WebEx. Thus, the ActiveX control is also an attack vector for this vulnerability. The vulnerability occurs when parsing the proprietary .wrf file format used to save recorded meetings. When parsing an integer value from the file, the vulnerable code uses this value in a calculation to determine how many bytes to allocate for a heap buffer. This arithmetic operation can overflow, which leads to an undersized buffer being allocated. This buffer is subsequently overflowed in a memory copy operation.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user viewing the web page or opening the file. There are multiple attack vectors for this vulnerability. The first attack vector involves the standalone WebEx Player. In order to exploit the vulnerability, a targeted user would have to open a '.wrf' file with the player. The second attack vector is through the browser using the ActiveX control. In order to trigger the vulnerability, the victim would have to choose to join the meeting by filling in their details and clicking the Join button on the web page. Thus, some degree of user interaction is involved in exploiting this vulnerability.

DETECTION

The following versions of WebEx WRF Player are vulnerable:

  • Client builds 27.32.0 (T27 LD SP32) and prior
  • Client builds 27.25.9 (T27 LC SP25 EP9) and prior
  • Client builds 27.21.10 (T27 LB SP21 EP10) and prior
  • Client builds 27.11.26 (T27 L SP11 EP26) and prior

WORKAROUND

In order to prevent browser-based exploitation, set the killbit for the Cisco WebEx ActiveX control. Its CLSID is "E06E2E99-0AA1-11D4-ABA6-0060082AA75C."

There is no workaround available for the standalone player, as disabling access to the DLL containing the vulnerability will render the player inoperable.

VENDOR RESPONSE

Cisco Systems Inc. has released updates which address this issue. For more information, consult their advisory at the following URL:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120404-webex

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-1337 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

01/04/2012 Initial Vendor Notification
01/04/2012 Initial Vendor Reply
04/04/2012 Coordinated Public Disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2012 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.