iDefense Security Advisory 02.08.11
http://labs.idefense.com/intelligence/vulnerabilities/
Feb 08, 2011

I. BACKGROUND

The Windows Picture and Fax Viewer "shimgvw.dll" library is used by
Windows Explorer to generate thumbnail previews for media files.

II. DESCRIPTION

Remote exploitation of a buffer overflow vulnerability in multiple
versions of Microsoft Corp.'s Windows could allow attackers to execute
arbitrary code on the targeted host. <BR><BR> An integer overflow
vulnerability exists in the "shimgvw" library. During the processing of
an image within a certain function, a bitmap containing a large
"biWidth" value can be used to cause an integer calculation overflow.
This condition can lead to the overflow of a heap buffer and may result
in the execute arbitrary code on the targeted host.

III. ANALYSIS

Exploitation could allow attackers to execute arbitrary code on the
targeted host under the privileges of the current logged-on user.
Successful exploitation would require the attacker to entice his or her
victim into viewing a specially-crafted thumbnail leveraging the
vulnerability. <BR><BR> Some vectors of attack include e-mail, the
browser and network shares. In an e-mail-based attack, the attacker
must entice his or her victim into opening or previewing a
specially-crafted Office document containing a specially-crafted
thumbnail. In a browser-based attack, the victim must simply view a
maliciously crafted website. In a network share attack, such as UNC or
WebDAV, an attacker would require the victim to simply navigate to the
folder containing the crafted thumbnail.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in Microsoft
Windows XP SP3. A full list of vulnerable Microsoft products can be
found in Microsoft Security Bulletin MS11-006.

V. WORKAROUND

Microsoft has included an automated Microsoft Fix it solution for the
Modify the Access Control List (ACL) on shimgvw.dll workaround, which
can be found at the following link:

http://support.microsoft.com/kb/2483185

VI. VENDOR RESPONSE

Microsoft Corp. has released patches which address this issue.
Information about downloadable vendor updates can be found by clicking
on the URLs shown.

http://www.microsoft.com/technet/security/bulletin/ms11-006.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2011-3970 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

01/12/2011  Initial Vendor Notification
01/12/2011  Initial Vendor Reply
02/08/2011  Coordinated Public Disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Kobi Pariente and Yaniv
Miron.

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X. LEGAL NOTICES

Copyright © 2011 iDefense, 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
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reliance on, this information.