A significant number of visits to Web pages could place consumer's computers at risk, security startup SiteAdvisor stated in a recent release.

The company, founded by graduate students from the Massachusetts Institute of Technology, uses a legion of automated virtual computers to scan the Internet for dangerous Web sites. SiteAdvisor has scanned sites that account for 95 percent of all Web traffic, rating the dangerous pages as 'red', questionable pages as 'yellow', and legitimate sites as 'green'. The company found that sites accounting for 5 percent of all Web traffic attempted to upload hostile programs to a visitor's computer, or acted in some other malicious way. Sites that accounted for another 2 percent of traffic received the company's yellow rating.

The automated virtual computers, also known as client-side honeypots or 'honeymonkeys', have been used to research current online threats by Microsoft and other companies. SiteAdvisor is the first attempt to turn the data generated by such computers into a service. Microsoft used its honeymonkeys to browse the riskier side of the Web for servers that use zero-day exploits against visitors. The University of Washington used similar techniques to survey the Web and find that one in twenty executables on the Internet contain spyware.

SiteAdvisor announced on Wednesday that the company had finished its preview release of the service and had rolled out its first trial version of the tool.