Pierluigi Paganini September 17, 2016

A researcher has demonstrated that the NAND mirroring technique was able to bypass the passcode retry limitations on the San Bernardino shooter’s iPhone.

The battle between the FBI and Apple for unlocking an iPhone 5C belonging to the San Bernardino shooter went in the headlines in the first part of the year. Apple refused to unlock the device, the FBI threatened the company of a legal action, but the dispute ended after the FBI paid to break into San Bernardino shooter’s iPhone.

Apple refused to unlock the device, the FBI threatened the company of a legal action, but the dispute ended after the FBI paid to break into San Bernardino shooter’s iPhone.

In April, FBI Director Comey explained at the Aspen Security Forum in London that the Agency paid more than $1.3 Million to break into San Bernardino shooter’s iPhoneInstead of spending so much money, the FBI could have hacked iPhone with just $100, you’ve got it right, $100!

Instead of spending so much money, the FBI could have hacked iPhone with just $100, you’ve got it right, $100!News of the day is that anyone can unlock an iPhone for less than $100!

A security researcher at the Cambridge University, Sergei Skorobogatov, has demonstrated that anyone can unlock an iPhone for less than $100!

Skorobogatov has published a paper that details a technique, dubbed NAND Mirroring, to bypass the iOS passcode limit, exactly the problem faced by the FBI when dealing with the San Bernardino shooter’s iPhone 5C.

“This was achieved by desoldering the NAND Flash chip of a sample phone in order to physically access its connection to the SoC and partially reverse engineering its proprietary bus protocol. The process does not require any expensive and sophisticated equipment. All needed parts are low cost and were obtained from local electronics distributors. By using the described and successful hardware mirroring process it was possible to bypass the limit on passcode retry attempts. ” reads the paper.

The NAND Mirroring technique was one of the methods proposed to the FBI that rejected it, but Skorobogatov  demonstrated the Bureau was wrong.

“It does not work,” explained the FBI Director James Comey.

Skorobogatov used off-the-shelf equipment to hack into an iPhone 5C running iOS 9.3. He removed the NAND memory chip from the iPhone circuit board and copied the data to a test board many times over.

Then the researcher tried to brute force the image of the data extracted from the NAND memory. According to the researchers, he found the correct code in around 20 hours, the time necessary to brute-force a four-digit passcode, and in a few weeks, he was able to discover a six-digit one.

“The mirroring solution presented in this paper was achieved using off-the-shelf components bought from an electronics distributor with a budget of under 100 dollars. The same approach could be applied to the newer models of iPhone. .” reads the paper.

The researcher demonstrated that the NAND mirroring technique also works on iPhone 5S as well as iPhone 6 devices, that use the name type of NAND Flash memory. The NAND mirroring could also be adapted to other iPhones using different NAND Flash memories.

Enjoy the paper, waiting for a comment from the FBI or Apple.

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Pierluigi Paganini

(Security Affairs – NAND Mirroting, iPhone)