Adobe Shockwave Lingo Script Opcodes Integer Signedness Vulnerability
06.14.11
BACKGROUND

Adobe Shockwave Player is a popular Web browser plug-in. It is available for multiple Web browsers and platforms, including Windows, and MacOS. Shockwave Player enables Web browsers to display rich multimedia content in the form of Shockwave videos. For more information, see the vendor's site found at the following link:

http://get.adobe.com/shockwave
DESCRIPTION

Remote exploitation of a integer signedness vulnerability in Adobe Systems Inc.'s Shockwave could allow an attacker to execute arbitrary code with the privileges of the current user.

This vulnerability occurs when Shockwave processes a maliciously constructed "Lscr" record. This record can embed Lingo script code, which is Shockwave's scripting language. The vulnerability occurs when processing certain opcodes. Specifically, a 32-bit value from the file is used as an offset into a heap buffer without proper validation. When comparing the value to the maximum buffer size, a signed comparison is performed. By using a negative value, it is possible to index outside of the allocated buffer. This results in data outside of the buffer being treated as a valid pointer, and this pointer is later used as the destination of a write operation. This can corrupt an arbitrary memory address, which 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. To exploit this vulnerability, a targeted user must load a malicious Web page created by an attacker. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. After the user visits the malicious Web page, no further user interaction is needed.
DETECTION

Shockwave Player version 11.5.9.620 and prior are vulnerable.
WORKAROUND

iDefense is currently unaware of any workarounds for this issue.
VENDOR RESPONSE

Adobe has addressed this issue with an update. Further details and patches can be found at the following URL.

http://www.adobe.com/support/security/bulletins/apsb11-17.html
CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-0335 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

05/18/2011 Initial Vendor Notification
05/18/2011 Initial Vendor Reply
06/14/2011 Coordinated Public Disclosure
CREDIT

This vulnerability was reported to iDefense by Luigi Auriemma.

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LEGAL NOTICES

Copyright © 2011 Verisign, Inc.

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