MS00-007: Shared Workstation Setup May Permit Access to Recycle Bin Files (248399)

SYMPTOMS

On a shared computer, it may be possible for a user to create a folder in the %SystemRoot\Recycler folder that is then assigned to another user based on the Security Identifier (SID) number. If you do this, a malicious user may assign themselves extended rights to the newly created Recycle Bin folder before it is assigned to another user.

This allows someone the ability to insert files into a user's Recycle Bin or permanently delete a user's files located in that specific Recycle Bin.

This vulnerability does not allow the malicious user to read the files in the Recycle Bin folder.

NOTE: This patch does not apply to computer's that use FAT partitions because disk security features cannot be enabled on these computers.

RESOLUTION

Windows NT 4.0

To resolve this problem, obtain the individual package referenced below or obtain the Windows NT 4.0 Security Rollup Package. For additional information on the SRP, click the article number below to view the article in the Microsoft Knowledge Base:

299444 Post-Windows NT 4.0 Service Pack 6a Security Rollup Package (SRP)

The following files are available for download from the Microsoft Download Center:

NOTE: This patch only applies to Internet Explorer 4.0 without Active Desktop enabled. If you apply this patch to a computer running IE 4.0 with Active Desktop enabled, it will appear that the patch installed correctly; however, Shell32.dll is not replaced.

x86: Download Q248399i.exe now

Alpha: Download Q248399a.exe now

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. The English-language version of this fix should have the following file attributes or later:

   Date       Time     Size        File name     Platform
   -------------------------------------------------------------
   01/18/00   02:47p   1,280,784   Shell32.dll   x86
   01/18/00   02:47p   1,857,808   Shell32.dll   Alpha

Windows NT Server 4.0, Terminal Server Edition

To resolve this problem, obtain the Windows NT Server 4.0, Terminal Server Edition, Security Rollup Package (SRP). For additional information about the SRP, click the article number below to view the article in the Microsoft Knowledge Base:

317636 Windows NT Server 4.0, TerminalServer Edition, Security Rollup Package

MORE INFORMATION

The Windows NT Recycle Bin for a user maps to a folder in %SystemRoot%\Recycler. The name of the folder is based on the owner's SID. The folder is created the first time the user deletes a file, and the owner is given the only permissions to it. However, if a malicious user can create the folder before the real one is created, that user could assign permissions that give them the ability to delete files from it or add files to it.

There are several significant limitations that make it extremely difficult to exploit this vulnerability. The malicious user would need to share a machine with the other user, and would need to create the bogus Recycle Bin before the user's bona fide folder were created. This vulnerability only enables the malicious user to take action against the Recycle Bin on the particular machine that is attacked. The vulnerability does not allow the malicious user to read any files in the other user's Recycle Bin, nor would it give him or her a means of inducing the other user to retrieve a bogus file from it.

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

http://www.microsoft.com/technet/security/bulletin/ms00-007.mspx

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

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