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Experts say 'chip off' procedure to access terrorist's iPhone is risky

Jeremy Kirk | March 10, 2016
An error in removing the iPhone's flash memory could make the data unreadable forever.

But computer forensics experts, including one who has performed the procedure, say it is slow and delicate with no guarantee of success.

Most chip-off extractions result in the device being destroyed, said Heather Mahalik, principal forensic scientist and team lead for Oceans Edge, a mobile security and development firm. She teaches an advanced smartphone forensics course at the SANS Institute.

"I have done chip off in the past, and getting the phone to work again after is very difficult, so the chances of this working are low," Mahalik said via email. 

Cindy Murphy, a computer forensics expert with the Madison, Wisconsin, police department, said it's neither easy nor simple to remove and replace flash memory.

"To do this once, let alone as many times as would be necessary to brute-force the passcode, would be a feat of patience and perseverance and likely wouldn’t be successful," she wrote via email.

If auto-erase is enabled, investigators would have to remove and replace the chip for every 10 wrong guesses. Apple also enforces a delay in between wrong guesses, increasing the amount of time it would take to guess the passcode through brute force.

"This would also be an extremely slow and manual process," said Sarah Edwards, a digital forensics analyst who also teaches a SANS course.

And if the procedure goes poorly, "then you get zero chances to get the data," she said.

 

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