Symbolic Link Case Sensitivity Exploit Bypasses System Security

This article was previously published under Q222159
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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.
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:
  • 152734 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:

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, 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 value, type 1, and then click OK.
  5. Quit Registry Editor, and then restart the computer.
Microsoft has confirmed that this is 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.

Article ID: 222159 - Last Review: 11/02/2013 18:43:00 - Revision: 4.0

  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Enterprise Edition
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