MS02-004: Telnet Server Is Vulnerable to a Denial-of-Service Attack

There is a buffer-overflow vulnerability that affects two Microsoft products: the Telnet service in Windows 2000 and the Telnet daemon (telnetd) in Microsoft Interix 2.2. By sending a specially malformed request to the Telnet server, an attacker could cause either of two results. In the simpler case, this could cause the Telnet server to stop working. In the more complex case, this could allow an attacker to run code of his or her choice on the server.

Microsoft strongly recommends that you use Telnet on only fully trusted networks. You should not use Telnet across the Internet; you should block Telnet connections at your corporate firewall. Neither Windows 2000 nor Interix is affected by by this vulnerability under default conditions.

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: The resolution for this problem is also included in the hotfix in this article and in Windows 2000 Security Rollup Package 1 (SRP1). For additional information about SRP1, click the article number below to view the article in the Microsoft Knowledge Base: The following files are available for download from the Microsoft Download Center:
Release Date: February 7, 2002

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

Internix 2.2

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that you determine are at risk of attack. Evaluate the computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to the computer. See the associated Microsoft Security Bulletin (http://www.microsoft.com/technet/security/bulletin/MS02-004.mspx) to help determine the degree of risk. This hotfix may receive additional testing. If the computer is sufficiently at risk, we recommend that you apply this hotfix now.

To resolve this problem immediately, download the hotfix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site: Note In special cases, charges that are ordinarily incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The following file is available for download from the Microsoft Download Center:
Release Date: February 7, 2002

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: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 secure servers that prevent any unauthorized changes to the file.

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

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows 2000 and Interix 2.2. This problem was first corrected in Windows 2000 Service Pack 3.

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