According to a new report, the FBI may have received a little help from so-called "professional hackers" in its successful bid to crack the iPhone 5c at the center of its recent legal feud with Apple. The Washington Post reports that the hackers pointed out a security flaw which was then exploited with a custom piece of hardware that allowed the FBI unlimited guesses at the iPhone's passcode.

The new information was then used to create a piece of hardware that helped the FBI to crack the iPhone's four-digit personal identification number without triggering a security feature that would have erased all the data, the individuals said.

Prior reports have suggested that the FBI secured help from Israeli firm Cellebrite in hacking the San Bernardino iPhone, but this was not the case, The Washington Post's anonymous sources say.

The exact method used to hack into the phone is still unknown. However, FBI Director James Comey has stated that the method does not work with the iPhone 5S or newer, limiting its potential uses going forward. It's still unclear whether the FBI intends to disclose its methods to Apple.