Software Engineering Institute

Microsoft FrontPage Server Extensions (FPSE) is an optional set of tools that adds functionality to a web site. This functionality includes remote server administration, content updates, and a variety of site-specific tools such as searching support and form handling. According to MS03-051, FPSE is installed by default on Internet Information Server (IIS) 4.0, 5.0, and 5.1.

The SmartHTML interpreter, a sub-component of FPSE, contains a denial of service vulnerability. According to Microsoft, a specially crafted request can cause the SmartHTML interpreter to enter a loop that will temporarily consume processor time and interrupt the normal operation of the server host.

This vulnerability allows unauthenticated remote attackers to conduct denial of service attacks against affected hosts.

Apply a patch from Microsoft

Microsoft has published Microsoft Security Bulletin MS03-051 to address this vulnerability. For a complete list of systems affected, please read the Microsoft bulletin.

Disable FrontPage Server Extensions

As a an interim measure, sites may reduce their exposure to this vulnerability by disabling FrontPage Server Extensions. Note that this may reduce the functionality of sites that utilize FPSE extensions.

Disable Internet Information Server

The IIS web server is installed by default on several versions of Microsoft Windows. As a general rule, the CERT/CC recommends that system administrators disable or remove any nonessential software. In this case, IIS should be removed from any host that is not expected to serve web pages.