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Q222159: Symbolic Link Case Sensitivity Exploit Bypasses System Security

Article: Q222159
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): kbWinNT400sp5fix
Last Modified: 16-MAY-2002

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The information in this article applies to:

- Microsoft Windows NT Server versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4 
- Microsoft Windows NT Workstation 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
========

When you modify the "\??" object folder's symbolic link table by substituting a
different case (upper versus lower) letter in the table to point to a different
device associated with a disk drive alias, it may be possible to bypass typical
Windows NT security and allow any user to acquire administrator privileges.

RESOLUTION
==========

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


Once you have installed the Windows NT 4.0 service pack, it is necessary to
enable base system object restrictions to prevent the use of this security
exploit. To do this:

1. Click Start, click Run, type "regedt32" (without the quotation marks), and
  then click OK.

2. On the Windows menu, click "HKEY_LOCAL_ MACHINE on Local Machine".

3. Double-click the \System\CurrentControlSet\Control\Session Manager folder.

4. Double-click the "ProtectionMode" (without the quotation marks) value, type
  "1" (without the quotation marks), and then click OK.

5. Quit Registry Editor, and then restart the computer.

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 4.0 Service Pack 5.

Additional query words:

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Keywords          : kbWinNT400sp5fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTW400sp4 kbWinNTW400sp3 kbWinNTW400sp2 kbWinNTW400sp1 kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400sp4 kbWinNTSEnt400 kbWinNTS400sp4 kbWinNTS400sp3 kbWinNTS400sp2 kbWinNTS400sp1 kbWinNTS400search kbWinNTS400
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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