Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2018/06/bypassing_passc.html
Last week, a story was going around explaining how to brute-force an iOS password. Basically, the trick was to plug the phone into an external keyboard and trying every PIN at once:
We reported Friday on Hickey’s findings, which claimed to be able to send all combinations of a user’s possible passcode in one go, by enumerating each code from 0000 to 9999, and concatenating the results in one string with no spaces. He explained that because this doesn’t give the software any breaks, the keyboard input routine takes priority over the device’s data-erasing feature.
I didn’t write about it, because it seemed too good to be true. A few days later, Apple pushed back on the findings — and it seems that it doesn’t work.
This isn’t to say that no one can break into an iPhone. We know that companies like Cellebrite and Grayshift are renting/selling iPhone unlock tools to law enforcement — which means governments and criminals can do the same thing — and that Apple is releasing a new feature called “restricted mode” that may make those hacks obsolete.
Grayshift is claiming that its technology will still work.
Former Apple security engineer Braden Thomas, who now works for a company called Grayshift, warned customers who had bought his GrayKey iPhone unlocking tool that iOS 11.3 would make it a bit harder for cops to get evidence and data out of seized iPhones. A change in the beta didn’t break GrayKey, but would require cops to use GrayKey on phones within a week of them being last unlocked.
“Starting with iOS 11.3, iOS saves the last time a device has been unlocked (either with biometrics or passcode) or was connected to an accessory or computer. If a full seven days (168 hours) elapse [sic] since the last time iOS saved one of these events, the Lightning port is entirely disabled,” Thomas wrote in a blog post published in a customer-only portal, which Motherboard obtained. “You cannot use it to sync or to connect to accessories. It is basically just a charging port at this point. This is termed USB Restricted Mode and it affects all devices that support iOS 11.3.”
Whether that’s real or marketing, we don’t know.