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Category:   Application (Generic)  >   DebugView Vendors:   Microsoft
Microsoft DebugView 'Dbgv.sys' Module Lets Local Users Gain Kernel Level Privileges
SecurityTracker Alert ID:  1018903
SecurityTracker URL:
CVE Reference:   CVE-2007-4223   (Links to External Site)
Date:  Nov 6 2007
Impact:   Root access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): prior to 4.72
Description:   A vulnerability was reported in Microsoft DebugView. A local user can obtain kernel level privileges on the target system.

A local user can cause the 'Dbgv.sys' kernel module to execute arbitrary code on the target system with kernel level privileges.

The DebugView application must be running (with administrator privileges) in order for arbitrary local users to access the vulnerable kernel module.

The vendor was notified on August 21, 2007.

Stephen Fewer of Harmony Security reported this vulnerability via iDefense.

Impact:   A local user can obtain kernel privileges on the target system.
Solution:   The vendor has released a fixed version (4.72).

No vendor advisory was available at the time of this entry.

Vendor URL: (Links to External Site)
Cause:   Access control error
Underlying OS:  Windows (Any)

Message History:   None.

 Source Message Contents

Subject:  iDefense Security Advisory 11.06.07: Microsoft DebugView Privilege

iDefense Security Advisory 11.06.07
Nov 06, 2007


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.


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.


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.


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


iDefense is currently unaware of any effective workaround for this


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


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 (, which standardizes names for
security problems.


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


This vulnerability was reported to VeriSign iDefense by Stephen Fewer of
Harmony Security (

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