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Cisco WebEx Player WRF JPEG DHT Chunk Stack Buffer Overflow Vulnerability



WebEx Player is used to play recorded WebEx meetings in the '.wrf' file format. More information is available at


Remote exploitation of a stack buffer 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 embedded JPEG file, the vulnerable code incorrectly handles a length value of a Define Huffman Table (DHT) JPEG marker. The result is that a fixed stack based buffer is overflowed with content from the file. This allows an attacker to overwrite critical data structures on the stack, including an object pointer used in the same function. This leads to the execution of arbitrary code.


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.


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


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.


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


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-3055 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


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


This vulnerability was reported to iDefense by Damian Put.

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Copyright © 2012 Verisign, Inc.

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