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Q231605: Malformed Help File Causes Help Utility to Stop Responding

Article: Q231605
Product(s): Microsoft Windows NT
Version(s): winnt:4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4
Operating System(s): 
Keyword(s): kbWinNT4sp6fix
Last Modified: 16-MAY-2002

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The information in this article applies to:

- Microsoft Windows NT Server version 4.0, Terminal Server Edition 
- Microsoft Windows NT Workstation versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4 
- Microsoft Windows NT Server versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4 
- Microsoft Windows NT Server, Enterprise Edition versions 4.0, 4.0 SP4 
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SYMPTOMS
========

A specially-malformed Microsoft Help file may be used to exploit a security
vulnerability on a Windows NT-based computer. When a user activates the Windows
Help file tool (for example, by pressing the F1 key) this vulnerability may be
used to run a program and may cause the Help file tool to stop responding
(hang).

CAUSE
=====

The Help tool parses and displays Help information for programs. The Help
information is contained in several file types that are generated by the
Microsoft Help Compiler program and are stored (by default) in the
%SystemRoot%\Help folder. Users have both Read and Write permissions to this
folder by default. An unchecked buffer exists in the Help utility, and a Help
file that has been carefully modified could be used to run a program on the
local computer using a buffer overrun technique. Because the Help Compiler
program's output files do not generate the specific malformation at issue here,
this vulnerability could not be accidentally exploited.

RESOLUTION
==========

Windows NT Server or Workstation 4.0
------------------------------------

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the
individual software update. For information on obtaining the latest service
pack, please go to:

- http://www.microsoft.com/Windows/ServicePacks/

-or-

- Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For information on obtaining the individual software update, contact Microsoft
Product Support Services. For a complete list of Microsoft Product Support
Services phone numbers and information on support costs, please go to the
following address on the World Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: This hotfix can be applied to computers running Windows NT 4.0 Service Pack
4 or Windows NT 4.0 Service Pack 5.


Windows NT Server 4.0, Terminal Server Edition
----------------------------------------------

To resolve this problem, obtain the latest service pack for 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 the Microsoft products that are
listed at the beginning of this article. This problem was first corrected in
Windows NT Server version 4.0, Terminal Server Edition Service Pack 6.

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

Computers primarily at risk from this vulnerability are workstations, terminal
servers, and other computers that allow users to log on interactively and add or
modify Help files. Servers generally do not allow normal users to interactively
log on. Note that this vulnerability would affect only the local computer; there
is no capability to directly attack a remote computer by means of this
vulnerability.

For related information on this problem, please visit the Web site at:

  http://www.microsoft.com/security/bulletins/MS99-015.asp

For additional security-related information about Microsoft products, please
visit the Web site at:

  http://www.microsoft.com/security/

Additional query words:

======================================================================
Keywords          : kbWinNT4sp6fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTW400sp4 kbWinNTW400sp3 kbWinNTW400sp2 kbWinNTW400sp1 kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400sp4 kbWinNTSEnt400 kbWinNTS400sp4 kbWinNTS400sp3 kbWinNTS400sp2 kbWinNTS400sp1 kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : winnt:4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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