iOS 12 comes with a simple yet powerful restricted access mode for USB accessories. Here’s how you can enable it on your iPhone and iPad.
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How USB Restricted Mode works in iOS 12
Apple first introduced USB Restricted Mode in iOS 11.4 firmware. This mode disabled access to USB accessories after a week.
iOS 12, too, comes with a powerful restricted access mode. However, iOS 12 restricts USB accessories to just one hour of access unless you unlock your device.
Once you unlock your Apple device, the timer will reset and it will take another hour for the restricted mode to kick in.
Apple implemented this feature to block passcode decryption tools like GrayKey unlock box by GrayShift Forensics.
Brute-force attacks rely on using a myriad of digit combinations and given enough time, can unlock any Apple device.
Surprisingly, there’s no dedicated section or option for this mode in the Settings app. Moreover, this mode is disabled by default on any device running iOS 12.
Which devices can work in restricted mode?
Once an hour passes, your iPhone’s Lightning port will turn into a charging port and lock out all other accessories.
Even connecting to “trusted” computers will no longer work unless you input a passcode.
Anyone who tries to connect any accessory during lockdown will receive “Unlock iPhone to use accessories” message.
Non-transfer devices, however, such as headphones and chargers would still continue to work in the event of a lockdown. Only accessories that involve data transfer are blocked.
Enabling USB Restricted Mode
Step 1 Open Settings.
Step 2 Scroll down and tap Touch ID & Passcode.
Step 3 Toggle USB Accessories off. This option is actually enabled by default. Once you disable it, USB accessories will no longer be able to access your device after an hour.
It is highly recommended that you enable USB Restricted Mode as soon as you install iOS 12 on your iPhone or iPad.
You never know when someone might try to hack into your smartphone or tablet.
What next?
Unfortunately, merely restricting USB accessories doesn’t guarantee that your device will be impervious to brute-force attacks.
Law enforcement agencies pay top dollar for powerful zero-day exploits. Hackers have developed exploits for every single iOS version out there and chances are iOS 12 won’t be able to hold on its own for too long.
Though all attempts performed after an hour will be rendered useless, your passcode can still get cracked in that one-hour window.
Your device only becomes secure after an hour passes after a USB accessory is connected to your device.
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