Date: Tue, 09 Dec 2008 15:50:39 -0500
From: iDefense Labs <labs-no-reply@...fense.com>
To: bugtraq@...urityfocus.com, vulnwatch@...nwatch.org, 
	full-disclosure@...ts.grok.org.uk
Subject: iDefense Security Advisory 12.09.08: Microsoft
 Windows Graphics Device Interface Integer Overflow Vulnerability

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iDefense Security Advisory 12.09.08
http://labs.idefense.com/intelligence/vulnerabilities/
Dec 09, 2008

I. BACKGROUND

Microsoft Windows graphics device interface (GDI) enables applications
to use graphics and formatted text on both the video display and the
printer. For more information about GDI, please visit the following Web
page: http://msdn2.microsoft.com/en-us/library/ms536795.aspx

II. DESCRIPTION

Remote exploitation of an integer overflow vulnerability in multiple
versions of Microsoft Corp.'s Windows operating system could allow an
attacker to execute arbitrary code with the privileges of the current
user.

This vulnerability exists in the way GDI handles integer math. An
integer overflow could occur while calculating the a buffer length,
which results in an undersized heap buffer being allocated. This buffer
is then overflowed with data from the input image file.

III. ANALYSIS

Exploitation allows an attacker to execute arbitrary code with the
privileges of the current user. Exploitation would require convincing a
targeted user to view a specially crafted image file. An attacker could
host this file on a Web server, attach the file to an e-mail or
embedded the file in an Office document.

This vulnerability also can be triggered through e-mail. If the e-mail
client can automatically display images embedded in the e-mail, the
user only needs to open the e-mail to trigger the vulnerability.
Currently an EMF file is used as a test attack vector. Outlook and
Outlook Express will automatically display EMF images and trigger the
vulnerability. Lotus Notes and Thunderbird do not display EMF images in
e-mail directly, but the vulnerability still can be triggered when
opening or viewing the EMF attachment.

IV. DETECTION

iDefense has confirmed that gdi32.dll file version 5.1.2600.3316, as
included in fully patched Windows XP Service Pack 2 as of May 2008, is
vulnerable. Other versions of Windows are suspected to be vulnerable.

V. WORKAROUND

Turning off metafile processing by modifying the registry mitigates this
threat. Under registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\GRE_Initialize create a DWORD entry "DisableMetaFiles"
and set it to 1.

Note 1: This does not affect processes that are already running, so you
might need to log off and log on again or restart the computer after
making the change. Note 2: It only blocks one attack vector through
Windows metafile. It is possibly to exploit this vulnerability through
other attack vectors.

Impact of Workaround: components relying on metafile processing might
not work properly, such as printing.

Viewing e-mail in plain text format mitigates e-mail-based attack.

VI. VENDOR RESPONSE

"The vulnerability could allow remote code execution if a user opens a
specially crafted WMF image file. An attacker who successfully
exploited this vulnerability could take complete control of an affected
system. An attacker could then install programs; view, change, or delete
data; or create new accounts."

Microsoft Corp. has released a patch which addresses this issue. For
more information, consult their advisory at the following URL.

http://www.microsoft.com/technet/security/Bulletin/ms08-071.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-2249 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

05/21/2008  Initial Vendor Notification
05/21/2008  Initial Vendor Reply
09/05/2008  Additional Information Provided to Vendor
10/14/2008  Additional Vendor Feedback
12/09/2008  Coordinated Public Disclosure

IX. CREDIT

This vulnerability was discovered by Jun Mao of iDefense based on a
submission from an anonymous contributor.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events
http://labs.idefense.com/

X. LEGAL NOTICES

Copyright © 2008 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@...fense.com 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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