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Q192132: STA Threads Lose Thread Token

Article: Q192132
Product(s): Microsoft Windows NT
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): kbWinNT400sp4fix
Last Modified: 10-AUG-2001

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The information in this article applies to:

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

If a Single Threaded Apartment (STA) thread sets a thread token on its apartment
thread, it may lose this token unexpectedly. As a result, secure calls to open
files, databases, and so on, can fail. This behavior is exhibited only by STA
servers; MTA servers are unaffected by this problem.

CAUSE
=====

This problem is caused by a bug in the COM/RPC runtime that causes it to
incorrectly revert the thread token after a call was dispatched to the STA.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or
Windows NT Server 4.0, Terminal Server Edition. For additional information,
please see the following article in the Microsoft Knowledge Base:

  Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack



STATUS
======

Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT
Server 4.0, Terminal Server Edition. This problem was first corrected in Windows
NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition
Service Pack 4.

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

COM server processes may set thread tokens on their threads for various reasons.
Secure calls from such threads will use the thread token in the access checks
performed by the operating system. If these threads also happen to host STA
objects, the token can be lost because of the above bug. Secure calls from the
threads will then use the process token for access checks, and this can lead to
different results from the first case. The problem usually manifests as
unexpected security failures in secure accesses made by such threads.

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Keywords          : kbWinNT400sp4fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : WinNT:4.0
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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