McAfee, which has tracked the riskiest most famous people on the Web for the last six years, announced in a press release that Watson had knocked Heidi Klum out of the number one spot.
[Related: Get local showtimes and tickets]
According to the antivirus company, cybercriminals track the latest celebrity gossip, then lure fans to fake sites that steal personal information and passwords.
Searches for photos and downloads of Watson do have a downside: Lookups on the Brit have a more than 12 percent chance to land on a malicious site. Instead of photos of the British star, a user can end up with a computer virus, annoying or intrusive software like ad spam or worse.
The 22-year-old leads the McAfee list, followed by the actors Jessica Biel, Eva Mendes and Selena Gomez. Other stars rounding out the cyberscary celebs for 2012: Halle Berry, Megan Fox, Shakira, Cameron Diaz, Salma Hayek, and Sofia Vergara.
This is the first year that the top 10 dangerous celebrities were all female, making women the more dangerous gender for now, at least when it comes to online crime. The comedian Jimmy Kimmel was the only man to make the top 20 list this year.
Watch Emma Watson in 'The Perks of Being a Wallflower' theatrical trailer: