iOS 11.4.1 brings USB Restricted Mode but it has a bug

JC Torres - Jul 9, 2018, 10:56 pm CST
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iOS 11.4.1 brings USB Restricted Mode but it has a bug

Some features just can’t seem to wait for a grand release. That seems to be the case for Apple’s latest controversial security feature which was initially expected for iOS 12 in a few months. It seems, however, that pressing matters may have forced Apple to almost silently roll out its USB Restricted Mode feature in the new iOS 11.4.1 update. But while it’s designed to keep out hackers, it currently has a bug that would render that feature almost moot.

USB Restricted Mode was most likely designed in response to hackers like Grayshift developing tools and methods to break into iOS devices. Those tools end up in lawmakers’ hands but, potentially, criminals as well. The way it works is that when an hour has lapsed without the iPhone or iPad being unlocked with a passcode, the Lightning-USB connection will disable any data transfer.

Apple curiously didn’t include the security in the release notes, probably to not alert “interested parties”. You can, however, find USB Restricted Mode under the Touch ID & Passcode section of the Settings app as “USB Accessories”. The toggle is off by default, which means Restricted Mode is enabled and you’ll need to unlock the device via passcode or Touch ID before USB data connection can work again.

Greyshift claimed it had already worked around that restriction but it might not have to, at least not for a while. Security researchers are ElcomSoft report that USB Restricted Mode seems to have a bug that resets the one-hour countdown when you plug in a USB accessory. Not all accessories work but, for their tests, they used the $39 Lightning to USB 3 Camera Adapter dongle.

This is, of course, most likely just an oversight rather than a hidden (mis)feature. It also doesn’t work if USB Restricted Mode has already been triggered (past the one-hour mark). While iOS 11.4.1 is likely the final update before iOS 12, this bug could force Apple to push out 11.4.2 quickly.


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