MS02-018: Patch Available for Access Violation in URL Error Handling Vulnerability

A denial of service (http://www.microsoft.com/security/portal/glossary.aspx) vulnerability exists in Internet Information Server (IIS) 4.0, Internet Information Services (IIS) 5.0, and IIS 5.1. By exploiting this vulnerability, an attacker can temporarily prevent a Web server from providing Web services.

This vulnerability does not allow any data on the system to be compromised, nor does it enable the attacker to gain any rights on the system.

Microsoft investigations to date suggest that this vulnerability only occurs in cases in which Front Page Server Extensions (FPSE) are installed on the system, although it is possible that it may also occur under other conditions.

This vulnerability occurs because IIS incorrectly handles the error condition that results when one of the ISAPI filters that FPSE installs receives a Uniform Resource Locator (URL) that exceeds the maximum permitted length. Although the problem is with IIS, and therefore can also occur in cases that involve additional Internet Server Application Programming Interface (ISAPI) filters, Microsoft investigations to date have not revealed any other cases in which this occurs.

Internet Information Services 5.1

The update for this problem is included in the "MS02-018: April 2002 Cumulative Patch for Internet Information Services". For additional information about how to obtain this patch, click the article number below to view the article in the Microsoft Knowledge Base:

Internet Information Services 5.0

The update for this problem is included in the "MS02-018: April 2002 Cumulative Patch for Internet Information Services". For additional information about how to obtain this patch, click the article number below to view the article in the Microsoft Knowledge Base: 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:

Internet Information Server 4.0

The update for this problem is included in the "MS02-018: April 2002 Cumulative Patch for Internet Information Services". For additional information about how to obtain this patch, click the article number below to view the article in the Microsoft Knowledge Base:

Internet Information Services 5.1

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Microsoft Internet Information Services 5.1.

Internet Information Services 5.0

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Microsoft Internet Information Services 5.0. This problem was first corrected in Windows 2000 Service Pack 3.

Internet Information Server 4.0

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Microsoft Internet Information Server 4.0.

For more information on these vulnerabilities, see 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: