The FBI office in Los Angeles is investigating a series of hacking incidents targeting high-profile victims.
"The FBI is investigating a person or group responsible for computer intrusions of high-profile figures," FBI spokeswoman Laura Eimiller told CNET in a phone interview today.
Eimiller said she couldn't say how many alleged victims there may have been, but estimated that there were "dozens." The investigation has been going on since late 2010, she said.
The news follows leaks of celebrity photos reported in previous months. In March, Vanessa Hudgens met with the FBI after nude photos of her were allegedly stolen from her Gmail account and released online, TMZ reported at the time.
It's unclear who is behind the Johansson incident and whether all of the reported cases are linked or even legitimate.
Unlike corporations, which typically shun publicity for hacking, celebrities--whose careers seem to rise and fall with headlines--may have a motivation for going public with hacking claims, either to get attention or to deflect bad publicity. Meanwhile, celebrities are an attractive target for headline-seeking hackers. Sometimes it's difficult to link the attack to a specific party.
That didn't appear to be the case with an incident that happened during the MTV Video Music Awards on August 28. That night someone posted a video on YouTube with the headline "Anonymous - My Little Pony KREAYSHAWN HACKED." It contains an anti-Semitic rant about Hollywood. Also that night, nude photos of the rapper were posted to her hacked Twitter account, according to the Huffington Post.
"We're simply here to facilitate the free flow of information from a place which was previously over looked, Hollywood," a representative from a group calling itself Hollywood Leaks told Gawker in an e-mail the day after the Kreayshawn photos were leaked. Hollywood Leaks promotes its activity on a Twitter account using the "HWLeaks" handle.
FBI spokeswoman Eimiller said she could not comment on whether the agency was looking at the Anonymous group as part of its investigation. "There are lots of hackers out there," she said.
Hollywood would be a new type of target for the Anonymous online activist collective, which previously has hacked () government agencies, law enforcement, foreign governments, and private corporations like Sony. Often, members of the group release sensitive e-mails, contact information, and other information pilfered from compromised servers, but they also have been known to organize distributed denial-of-service attacks at victims, which can shut the Web sites down temporarily.
While the recent reports of celebrity hacking date back to March, the Hollywood Leaks Twitter account appears to have been operating since only August 19, claiming credit for the release of phone numbers for David Spade, Miley Cyrus, and Ashley Tisdale, among others, as well as the leak of a copy of the Tom Cruise film "Rock of Ages," which is due out next year.
Updated 8:55 p.m. PT with information related to Twitter account that promotes celebrity leaks.