Public Vulnerability Reports

Cisco WebEx Player WRF File Audio Size Heap Overflow Vulnerability

06.27.12

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 a heap 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 to control the number of bytes copied to a fixed size heap buffer. The target buffer is allocated to be a fixed 0x418 bytes, and it's possible to overflow this buffer with limited content of a near arbitrary length. This can lead to the execution of arbitrary code.

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 targets the standalone WebEx Player. In order to exploit the vulnerability through the Player, a targeted user would have to open a ".wrf" file with the player. An attacker typically accomplishes this by e-mailing the targeted user a malicious a file, or by embedding a link to a file in a webpage. The second attack vector is through the browser using the ActiveX control. In order to trigger the vulnerability through the browser, the victim would have to choose to join the meeting by filling in his or her 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 28.0.0 (T28 L10N)
  • Client builds 27.32.1 (T27 LD SP32 CP1) and prior
  • Client builds 27.25.10 (T27 LC SP25 EP10) 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-20120627-webex

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-3057 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

01/06/2012 Initial Vendor Notification
01/06/2012 Initial Vendor Reply
06/27/2012 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by Damian Put.

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LEGAL NOTICES

Copyright © 2012 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

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.