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Security Update, June 18, 2001

This update resolves the "Unchecked Buffer in Index Server ISAPI Extension Could Enable Web Server Compromise" security vulnerability in Windows NT® 4.0 computers running Internet Information Server (IIS) 4.0, and is discussed in Microsoft Security Bulletin MS01-033. Download now to help prevent a malicious user from taking control of your Web server.

The Index Server ISAPI (Index Server Application Programming Interface) extension, idq.dll file, which installs as part of Index Server 2.0 in Windows NT 4.0, has an unchecked buffer (a temporary data storage area that has a limited capacity) in the code that handles incoming requests. A specifically malformed request from a malicious user can cause the buffer to overflow. Doing so grants the malicious user Local System privileges, allowing him or her to take complete control of the Web server. This update eliminates the vulnerability by ensuring that the ISAPI extension checks input correctly.

Note Although the functionality provided by the idq.dll file supports Index Server 2.0, idq.dll is installed with IIS 4.0, and the vulnerability is present only when IIS 4.0 is running.

For more information about this vulnerability, read Microsoft Security Bulletin MS01-033. (This site is in English).

System Requirements
This update applies to Windows NT 4.0 computers running IIS 4.0.

How to use
Restart your computer to complete the installation.

How to uninstall

1. Click Start, point to Settings, and then click Control Panel.
2. Double-click Add/Remove Programs.
3. Select Windows NT Hotfix (Pre SP7) [See Q300972 for more information], and then click Add/Remove to uninstall.

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