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iDefense Security Advisory 12.14.10: Microsoft Internet Explorer CSS Style Table Layout Uninitialized Memory Vulnerability
Dec 14 2010 09:10PM
labs-no-reply (labs-no-reply ivcp vrsn com)
iDefense Security Advisory 12.14.10
Dec 14, 2010
Internet Explorer is a graphical web browser developed by Microsoft
Corp. that has been included with Microsoft Windows since 1995. For
more information about Internet Explorer, please the visit following
Remote exploitation of a memory corruption vulnerability in Microsoft
Corp.'s Internet Explorer could allow an attacker to execute arbitrary
code with the privileges of the current user.
The vulnerability exists due to an uninitialized variable in the
"CLayout::EnsureDispNode" method. This method is called to recalculate
the location of various HTML elements within the page. This function
passes a "CDispNodeInfo" object to another function,
"CLayout::GetDispNodeInfo," which is supposed to initialize the object
passed in; however, the function fails to properly initialize a flag's
value that is used later to determine how many "extra" bytes to
allocate for a heap buffer. This eventually leads to an undersized
buffer being allocated to hold a "CDispClipNode" object in the
"CLayout::EnsureDispNodeCore" function. The vulnerability manifests
itself when the "CDispNode::SetUserClip" function attempts to use the
invalid "extra size" to calculate an offset into the object and
manipulate a bit at this location. This corrupts the objects VTABLE by
setting the second bit to 1, which can lead to the execution of
arbitrary code when this pointer is accessed later.
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. 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.
Microsoft Internet Explorer 6, 7 and 8 are vulnerable.
Microsoft suggested workarounds can be found in Microsoft Security
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.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2010-3962 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
VIII. DISCLOSURE TIMELINE
08/11/2010 Initial Vendor Notification
08/11/2010 Initial Vendor Reply
12/14/2010 Coordinated Public Disclosure
This vulnerability was reported to iDefense by José Antonio Vázquez
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X. LEGAL NOTICES
Copyright © 2010 iDefense, 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 customerservice (at) idefense (dot) com [email concealed] 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.
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