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MS01-031: Telnet Service Prevents an Idle Telnet Session from Timing Out

Article ID: 282806 - View products that this article applies to.

This article was previously published under Q282806

SYMPTOMS

A denial-of-service vulnerability exists in the Windows 2000 Telnet service that can prevent an idle Telnet session from timing out. By starting as many sessions as the server could accommodate, and letting them idle in a particular way, an attacker could prevent other users from establishing Telnet sessions.

Mitigating Factors

It would not be necessary to reboot the server to recover from this vulnerability. At worst, the Telnet service would need to be restarted.
This vulnerability cannot be used to gain additional privileges on the computer; it is a denial-of-service vulnerability only.

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RESOLUTION

To resolve this problem, either obtain Windows 2000 Service Pack 3 or Windows 2000 Security Rollup Package 1 (SRP1). 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

(http://support.microsoft.com/kb/260910/EN-US/ )

How to Obtain the Latest Windows 2000 Service Pack

For additional information about SRP1, click the article number below to view the article in the Microsoft Knowledge Base:

311401

(http://support.microsoft.com/kb/311401/EN-US/ )

Windows 2000 Security Rollup Package 1 (SRP1), January 2002

The following file is available for download from the Microsoft Download Center:

Collapse this imageExpand this image

Download Q299553_w2k_sp3_x86_en.exe now

(http://www.microsoft.com/downloads/details.aspx?FamilyId=0D0032E7-259D-4F68-BF08-B0A7CAA1FD1C&displaylang=en)

Release Date: June 7, 2001

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

(http://support.microsoft.com/kb/119591/EN-US/ )

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 version of this fix should have the following file attributes or later:

   Date        Time    Version      Size     File name
   -----------------------------------------------------
   05/24/2001  04:14p  5.0.33667.1  186,128  Tlntsvr.exe

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STATUS

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Microsoft Windows 2000. This problem was first corrected in Windows 2000 Service Pack 3.

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MORE INFORMATION

For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base:

265173

(http://support.microsoft.com/kb/265173/EN-US/ )

The Datacenter Program and Windows 2000 Datacenter Server Product

For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:

296861

(http://support.microsoft.com/kb/296861/EN-US/ )

Use QChain.exe to Install Multiple Hotfixes with One Reboot

For additional information about what is fixed by this patch, click the article number below to view the article in the Microsoft Knowledge Base:

300855

(http://support.microsoft.com/kb/300855/EN-US/ )

Windows 2000 Telnet Security Rollup

For more information about this vulnerability, see the following Microsoft Web site:

http://www.microsoft.com/technet/security/bulletin/MS01-031.mspx

(http://www.microsoft.com/technet/security/bulletin/MS01-031.mspx)

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