System Crashes When Unprivileged User Accesses Privileged IOCTL (239931)


The information in this article applies to:

  • Microsoft Windows NT Server 4.0
  • Microsoft Windows NT Workstation 4.0
  • Microsoft Windows NT Server, Enterprise Edition 4.0
This article was previously published under Q239931

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 that this is 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.
Modification Type:MajorLast Reviewed:8/10/2001
Keywords:kbbug KB239931
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