Substituted Drives Are Persistent for Users on a Computer

This article was previously published under Q265351
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Drives that are created by using the subst command are persistent among users who log on to the same computer unless the drives are explicitly removed or the computer is rebooted. This could allow a user to "spoof" another user's drive letter.
MS-DOS device names are global. After it is defined, an MS-DOS device name remains visible to all processes until either it is explicitly removed or the computer is rebooted.
To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
260910 How to Obtain the Latest Windows 2000 Service Pack
The English version of this fix should have the following file attributes or later:
   Date        Time    Version        Size     File name   --------------------------------------------------------   06/12/2000  9:36PM  5.0.2195.2096  41,232   Basesrv.dll     06/12/2000  9:36PM  5.0.2195.2096  331,536  Msgina.dll    06/12/2000  9:37PM  5.0.2195.2096  177,936  Winlogon.exe  				

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 2000 Service Pack 2.
For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:
249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes
In Windows 2000, a strong access control list is now enabled by default to prevent spoofing attacks or privilege escalation attacks. The fix described in this article addresses potential attacks in the console session, and it enables non-administrators to use the subst /d command at the console.

Subst drives live in the MS-DOS devices namespace, which contains a large array of legacy devices. If the namespace uses a weak access control list, someone could hijack these devices or create a device with a malicious target.

Note You still cannot use the subst /d command to delete drive letters from a Windows 2000 Terminal Server session. This fix affects only the Console (session 0).

For more information about MS-DOS devices, please visit the following Microsoft Web site:

Article ID: 265351 - Last Review: 10/20/2013 21:59:11 - Revision: 4.4

Microsoft Windows 2000 Server, Microsoft Windows 2000 Advanced Server, Microsoft Windows 2000 Professional Edition

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