Microsoft KB Archive/262694

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

Article ID: 262694

Article Last Modified on 3/1/2007

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition Service Pack 4
 * Microsoft Windows NT Server 4.0, Terminal Server Edition Service Pack 5
 * 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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This article was previously published under Q262694



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



SYMPTOMS
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 the following Microsoft Web site:

http://www.microsoft.com/technet/security/bulletin/fq00-036.mspx



CAUSE
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 the Microsoft 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:

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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

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:

US English:

x86:

Download Q262694i.exe now

Alpha:

Download Q262694a.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 05/22/2000 08:34p  265,712  Rdr.sys    x86 05/22/2000 08:32p  508,720  Rdr.sys    Alpha

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.

Windows NT 4.0
Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows NT 4.0 and Windows NT Server version 4.0, Terminal Server Edition.



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:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MrxSmb\Parameters\RefuseReset

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

Additional query words: security_patch kbtsesrp

Keywords: kbhotfixserver kbqfe kbbug kbenv kbfix kbgraphxlinkcritical kbsecbulletin kbsecurity kbsecvulnerability kbwin2000presp2fix KB262694

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