iDefense Security Advisory 11.06.07
http://labs.idefense.com/intelligence/vulnerabilities/
Nov 06, 2007

I. BACKGROUND

DebugView is a system analysis tool designed to display debug messages
being generated on the system. More information is available on the
vendor's site at the following URL.

http://www.microsoft.com/technet/sysinternals/utilities/debugview.mspx

II. DESCRIPTION

Local exploitation of a design error vulnerability in Microsoft's
DebugView could allow attackers to execute arbitrary kernel code.

As part of its design, DebugView loads a kernel module Dbgv.sys. This
module includes functionality that can be abused to copy user supplied
data into the kernel, to controlled addresses. This allows malicious
users to inject arbitrary code into the running kernel.

III. ANALYSIS

Exploitation allows attackers to modify the kernel, resulting in the
arbitrary execution of code in kernel context.

In order to exploit this vulnerability, an administrator must launch the
DebugView application, which will load the Dbgv.sys driver into the
kernel. Once loaded, the vulnerable kernel module will be accessible by
all users, and will remain loaded until the system is rebooted.

IV. DETECTION

iDefense confirmed the existence of this vulnerability in Microsoft
DebugView version 4.64. The specific file version of Dbgv.sys is
4.60.0.0. This file is deleted automatically after being loaded and
will not be found on disk. Previous versions are suspected to be
vulnerable as well.

V. WORKAROUND

iDefense is currently unaware of any effective workaround for this
issue.

VI. VENDOR RESPONSE

Microsoft Sysinternals has addressed this vulnerability by releasing
version 4.72 of DebugView. For more information, visit the following
URL.

http://www.microsoft.com/technet/sysinternals/utilities/debugview.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-4223 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

08/21/2007  Initial vendor notification
08/21/2007  Initial vendor response
11/06/2007  Public disclosure

IX. CREDIT

This vulnerability was reported to VeriSign iDefense by Stephen Fewer of
Harmony Security (www.harmonysecurity.com)

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X. LEGAL NOTICES

Copyright © 2007 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
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