According to McAfee, the film star's name is more likely to direct a user to malicious sites than any other celebrity moniker.
The security firm found that fans who search the name "Brad Pitt" on the web have nearly a 1 in 5 chance of encountering a potentially risky site.
18 per cent of searches lead to wallpaper, screen savers and photos that carried some sort of malware. Searching 'Brad Pitt screensavers' bumps the infection risk up to 50 per cent.
Actress and pop star Beyonce was rated as the second most dangerous celebrity query. McAfee warned that searching for the singer's ringtones was particularly risky for users and could lead to both malware infection and stolen personal information.
Third on the list was Justin Timberlake, whose various public romances have made him a hot target for searches and a prime lure for malware writers. Timberlake was followed by actress Heidi Montag, singer Mariah Carey and actress Jessica Alba.
Rounding out the list of riskiest searches are Lindsey Lohan, Cameron Diaz, George Clooney and Angelina Jolie, who was the subject of a major malware attack earlier this year.
McAfee senior vice president of product development Jeff Green said that popular culture and celebrity sites have become fertile breeding grounds for malware in recent years, and that users should be careful when looking for the latest celebrity dirt.
"Because of Americans' obsession with following celebrities' lifestyles, they are an obvious target," said Green.
"We have to take precautions in casually navigating the Web since many subtle sites may be rife with malware for consumers' computers."