Kate Upton
Above: Model Kate Upton at a premiere for the film "The Other Woman" in Munich April 7, 2014. Upton was one of dozens of celebrities targeted by a nude photo scandal Sunday. Reuters

The nude celebrity photos that leaked on 4chan may have been obtained using one of the oldest hacker tricks in the book: phishing. Authorities are reporting that the FBI is looking into the possibility that some of the high-profile celebrities targeted in the leak, such as model Kate Upton and actors Jennifer Lawrence, Lea Michele and Mary Elizabeth Winstead, may have fallen victim to voluntarily sharing their personal information with hackers.

“FBI investigators are looking into whether Kate and at least 3 other celebs were prime targets of phishing,” TMZ reported Thursday. Law enforcement officials sources say the stars are believed to have received a doctored email appearing to be from Apple regarding a false problem with their account in which they were asked to share their passwords and other personal information.

The leaked images were previously believed to have been obtained via a flaw in one of Apple’s systems, which the company denied in a statement Tuesday. After a two-day investigation, Apple reported that a breach did not occur within their iCloud or Find my iPhone systems, but that the celebrity accounts were compromised in a "targeted attack."

The FBI confirmed its involvement in the nude celebrity hacking scandal Monday, with a spokesperson telling the Los Angeles Times, “The FBI is aware of the allegations concerning computer intrusions and the unlawful release of material involving high profile individuals and is addressing the matter.”