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Category:   Application (Generic)  >   WinPcap Vendors:
WinPcap Input Validation Flaw in NPF.SYS Driver Lets Local Users Gain Elevated Privileges
SecurityTracker Alert ID:  1018350
SecurityTracker URL:
CVE Reference:   CVE-2007-3681   (Links to External Site)
Updated:  May 6 2008
Original Entry Date:  Jul 10 2007
Impact:   Execution of arbitrary code via local system, Root access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 4.x prior to 4.1
Description:   A vulnerability was reported in WinPcap. A local user can obtain system privileges on the target system.

A local user can exploit an input validation flaw in the NPF.SYS driver to execute arbitrary code on the target system with kernel-level privileges.

Interrupt Request Packet parameters passed to IOCTL 9031 (BIOCGSTATS) are affected.

The vendor was notified on May 16, 2007.

Mario Ballano from reported this vulnerability to iDefense.

Impact:   A local user can obtain kernel-level privileges on the target system.
Solution:   The vendor has issued a fixed version (4.0.1).

The vendor's advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Input validation error
Underlying OS:  Windows (Any)

Message History:   None.

 Source Message Contents

Subject:  iDefense Security Advisory 07.09.07: WinPcap NPF.SYS Local Privilege

WinPcap NPF.SYS Local Privilege Escalation Vulnerability

iDefense Security Advisory 07.09.07
Jul 09, 2007


WinPcap is a software package that facilitates real-time link-level
network access for Windows-based operating systems. It is used by a
wide range of open-source projects including Wireshark. More
information is available at the project web site at the URL shown


Local exploitation of an input validation vulnerability within the
NPF.SYS device driver of WinPcap allows attackers to execute arbitrary
code in kernel context.

The vulnerability specifically exists due to insufficient input
validation when handling the Interrupt Request Packet (Irp) parameters
passed to IOCTL 9031 (BIOCGSTATS). By passing carefully chosen
parameters to this IOCTL, an attacker can overwrite arbitrary kernel


Exploitation allows attackers to execute arbitrary code in kernel

The vulnerable device driver is loaded when WinPcap is initialized. This
driver can be set to load on start-up depending on a choice made at
installation time. This is not the default setting.

In a default installation, the device driver is not loaded until an
Administrator utilizes a WinPcap dependent application. Once they do,
it will become accessible to normal users as well. When a program using
this driver exists, it is not unloaded. Attackers will continue to have
access until the driver is manually unloaded.

If the option to allow normal user access was chosen at installation
time, attackers will always have access to this device driver.
Consequently, a local attacker without administrator privileges would
have access to sniff, as well as exploit this vulnerability.


iDefense has confirmed the existence of this vulnerability in version
4.0 of WinPcap as included in Wireshark 0.99.5. The version of NPF.SYS
tested was Older versions are suspected to be vulnerable.


iDefense is currently unaware of any effective workaround for this


The WinPcap Team has addressed this vulnerability by releasing version
4.0.1 of the WinPcap software. For more information, see the following


A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.


05/16/2007  Initial vendor notification
05/16/2007  Initial vendor response
07/09/2007  Coordinated public disclosure


This vulnerability was reported to iDefense by Mario Ballano from

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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 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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