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)
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 © 2007 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
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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.
