IOS 11.4.1's New Passcode Cracking Prevention Feature Can Be Bypassed: ElcomSoft

Yolanda Curtis
July 10, 2018

It's worth pointing out that if you would like to immediately require authorisation for USB accessories, you can do the same trick that disables Face ID and Touch ID temporaily: simply hold down the side buttons until the "Slide to power off" screen appears.

The accompanying explanation gives no indication of its real objective: "Unlock iPhone to allow USB accessories to connect when it has been more than hour since your iPhone was locked", it says underneath a sliding bar.

Back when Apple first revealed that it would be implementing USB Restricted Mode in iOS, the company caught some backlash from U.S. authorities.


With the lock in place, data cannot be transferred to or from the Lightning port; it can only be used for device charging.

However, security firm Elcomsoft noted in a blog post that you can reset this one-hour timer by plugging in a USB accessory - like this Lightning to USB 3 Camera Adapter that Apple itself makes - before the feature kicks in, so as to buy time to transport the phone back to a secure facility for investigation.

If however someone does get to a phone within that hour period, they can shove in a USB accessory and prevent the smartphone from going into restricted mode until they have a chance to attach a cracking box later on. However, as Oleg Afonin of ElcomSoft has highlighted, the feature is of no use if a USB accessory is already connected to your hardware. The resetting of the built-in feature works even with an untrusted USB accessory, one that has never been paired with the device before. Once an iPhone has been locked, a countdown begins before USB Restricted Mode activates.


The research team isn't sure if third-party adaptors have a similar effect, but this same method can't be achieved with Apple's Lightning to 3.5mm adaptor.

iOS 11.4.1 arrives 41 days after Apple released iOS 11.4 to all users. What's new in tvOS 11.4.1 This update includes general performance and stability improvements. iPhone users running iOS 11.4 right now have been complaining in droves that battery life has suffered after the update. However, this doesn't mean that the USB connectivity with an Apple device is entirely safe.


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