The study examined popular categories of Web sites including games, news and celebrity sites. Among the findings:

  • More 5 percent of executable files contain piggybacked spyware.
  • One in 62 Internet domains performs "drive-by download attacks" to force spyware on users who simply visit the site.
  • Game and celebrity Web sites appeared to pose the greatest risk for piggybacked spyware, while sites that offer pirated software topped the list for drive-by attacks.