Microsoft 's experimental Honeymonkey project has found almost 750 Web pages that attempt to load malicious code onto visitors' computers and detected an attack using a vulnerability that had not been publicly disclosed, the software giant said in a paper released this month.

Known more formerly as the Strider Honeymonkey Exploit Detection System, the project uses automated Windows XP clients to surf questionable parts of the Web looking for sites that compromise the systems without any user interaction. In the latest experiments, Microsoft has identified 752 specific addresses owned by 287 Web sites that contain programs able to install themselves on a completely unpatched Windows XP system.

Honeymonkeys, a name coined by Microsoft, modify the concept of honeypots--computers that are placed online and monitored to detect attacks.

"The honeymonkey client goes (to malicious Web sites) and gets exploited rather than waiting to get attacked," said Yi-Min Wang, manager of Microsoft's Cybersecurity and Systems Management Research Group. "This technique is useful for basically any company that wants to find out whether their software is being exploited this way by Web sites on the Internet."