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MS00-036: Malicious User Can Shut Down Computer Browser Service

This article was previously published under Q262694
This article has been archived. It is offered "as is" and will no longer be updated.
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
Microsoft has identified a vulnerability in the computer browser protocol ResetBrowser frame that could allow a malicious user to shut down a computer browser on the same subnet, or shut down all of the computers browsers on the same subnet. If all of the computers on the same subnet are shut down, they can then declare their own computer the new master browser.

NOTE: If a firewall is in place and port 138 UDP is blocked, this vulnerability cannot be exploited by an external user.

Additional information about this issue is available from thefollowing Microsoft Web site:
This behavior occurs because the ResetBrowser frame allows browsers to be shut down, but does not allow for a computer to ignore the ResetBrowser frames request.

Windows 2000

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
After you apply the following patch, you can configure computers to refuse ResetBrowser packets.This update is part of the Windows 2000 Security Update, June 6, 2000 that is available on the Windows Update site. You can also download this critical update (for installation later or on a different computer) from the following Microsoft Web sites:The English-language version of this fix should have the following file attributes or later:
   Date        Time     Version         Size     File name   --------------------------------------------------------   05/16/2000  07:35p   5.0.2195.2096   368,976  Mrxsmb.sys				

Microsoft Windows NT Server version 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

Windows 2000

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows 2000. This problem was first corrected in Windows 2000 Service Pack 2.
More information
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

RefuseReset Registry Entry

The patch provides functionality that allows an administrator to configure a computer to ignore ResetBrowser frames. To implement the patch, create the following registry key:
NOTE: Set the DWORD value of the key to 0x01 to ignore ResetBrowser frames and to None to accept ResetBrowser frames.

For additional information about what this patch fixes in Windows NT 4.0, click the article number below to view the article in the Microsoft Knowledge Base:
263307 Malicious User Can Fill Browser Announcement List Past Reasonable Limits
security_patch kbtsesrp

Article ID: 262694 - Last Review: 12/05/2015 20:13:37 - Revision: 7.0

Microsoft Windows NT Server 4.0, Terminal Server Edition Service Pack 6, Microsoft Windows 2000 Server, Microsoft Windows 2000 Advanced Server, Microsoft Windows 2000 Professional Edition, 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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