MS01-031: Predictable Named Pipes Could Enable Privilege Elevation with Telnet

Two privilege-elevation vulnerabilities exist in the Windows 2000 Telnet service that could enable an attacker to gain full control over an affected server, and enable the attacker to take any action on the server.

When a new Telnet session is established, the service creates a named pipe and runs any code that is associated with the named pipe as part of the initialization process. However, the pipe's name is predictable, and if Telnet finds an existing pipe with that name, it uses the existing pipe. An attacker who had the ability to load and run code on the server could create the pipe and associate a program with it; the Telnet service would run the code in the Local System context when it established the next Telnet session.

Mitigating Factors

• Because the attacker would need the ability to load and run code on the Telnet server, it is likely that these vulnerabilities could only be exploited by an attacker who had the ability to run code locally on the Telnet server.
• Administrative privileges are necessary to start the Telnet service, so the attacker could only exploit the vulnerability if Telnet were already started on the computer.

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: For additional information about SRP1, click the article number below to view the article in the Microsoft Knowledge Base: The following file is available for download from the Microsoft Download Center:
Release Date: Thursday, 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: 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:

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.

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: For additional information about what is fixed by this patch, click the article number below to view the article in the Microsoft Knowledge Base: For more information about this vulnerability, see the following Microsoft Web site: