Despite the FBI already achieving success in unlocking the encryption-protected iPhone 5c used by one of the perpetrators in the San Bernardino shooting in 2015, the bureau has not yet stopped in pushing Apple to unlock iPhones. The Justice Department has said that it is now prodding Apple to unlock an iPhone 5s related to a drug case in New York reported in March.

The iPhone encryption debacle continues, with the latest on the issue reported by the Washington Post.

According to the report, the FBI was able to breach the encryption on the iPhone 5c recovered from one of the San Bernardino terrorists by paying professional hackers.

The gray hat hackers were able to take advantage of a previously unknown flaw in iOS 9, according to sources familiar with the matter. The flaw was used by the hackers to create hardware that helped the FBI in cracking the four-digit PIN that was protecting the iPhone 5c in question.

The device was successfully unlocked without activating the security feature that would have wiped out all the data contained in the smartphone.

The researchers, which were paid a one-time fee for their efforts, were said to be low-profile hackers who focus on seeking out software vulnerabilities. In certain cases, they sold some of their discoveries to the United States government, a move that has earned them the tag of being gray hat hackers.

White hat hackers report vulnerabilities that they find in software to the companies that own them, while black hat hackers take advantage of flaws to steal sensitive information and breach networks.

Gray hat hackers, on the other hand, sell the vulnerabilities that they discover to parties such as the government and surveillance companies. Their controversial actions could lead to bad things such as undisclosed government surveillance measures, but they could also lead to good things such as systems that can track terrorist activities.

The report confirms previous news that the FBI was able to break through the iPhone 5c's encryption without the help of Israel-based Cellebrite Mobile Synchronization, despite the firm receiving its biggest FBI contract worth $218,000 on the same day that the FBI said a solution has been found for the iPhone's security wall.