DOCUMENT:Q239931  10-AUG-2001  [winnt]
TITLE   :System Crashes When Unprivileged User Accesses Privileged IOCTL
PRODUCT :Microsoft Windows NT
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft Windows NT Server version 4.0 
 - Microsoft Windows NT Workstation version 4.0 
 - Microsoft Windows NT Server, Enterprise Edition version 4.0 
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SYMPTOMS
========

When a user without the proper security privileges gains access to an
Input/Output Control (IOCTL) with high security priveleges either by opening the
device with trailing characters, using a relative open, or by obtaining the
transport handle from the Windows Sockets Support driver (Afd.sys), the computer
may stop responding (hang) and you may receive a STOP error message on a blue
screen similar to the message listed below:

   STOP 0X0000001E: KMODE_EXCEPTION_NOT_HANDLED

CAUSE
=====

This behavior occurs because any access to an IOCTL needs to be available for
users without the proper security privileges.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT 4.0.

MORE INFORMATION
================

An IOCTL is a custom class of Input/Output Request Packets (IRP) available to
User mode. Each Windows Driver Model (WDM) class driver has a set of IOCTLs that
it uses to communicate with programs. The IOCTLs give the class driver
information about intended usage by programs. The class driver performs all
IOCTL parameter validation.

Additional query words: TCP/IP

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Keywords          :  
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400 kbWinNTS400search kbWinNTS400
Version           : winnt:4.0
Issue type        : kbbug
Solution Type     : kbfix

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