[NT] WinPcap NPF.SYS Local Privilege Escalation Vulnerability

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WinPcap NPF.SYS Local Privilege Escalation Vulnerability
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SUMMARY

<http://www.winpcap.org/> 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".
Local exploitation of an input validation vulnerability within the NPF.SYS
device driver of WinPcap allows attackers to execute arbitrary code in
kernel context.

DETAILS

Vulnerable Systems:
* Wireshark version 0.99.5 with NPF.SYS version 4.0.0.755

Immune Systems:
* Wireshark version 0.99.5 with NPF.SYS version 4.0.1 or newer

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 memory.

Analysis:
Exploitation allows attackers to execute arbitrary code in kernel context.

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.

Vendor response:
The WinPcap Team has addressed this vulnerability by releasing version
4.0.1 of the WinPcap software. For more information, see the following
URL: <http://www.winpcap.org/misc/changelog.htm>

http://www.winpcap.org/misc/changelog.htm

Disclosure timeline:
05/16/2007 - Initial vendor notification
05/16/2007 - Initial vendor response
07/09/2007 - Coordinated public disclosure

ADDITIONAL INFORMATION

The information has been provided by Mario Ballano from 48bits.com.
The original article can be found at:
<http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=550>

http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=550

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