iOS 18 Security Feature Causes iPhone to Reboot After Three Days of Inactivity

[MacRumors]

With iOS 18, Apple introduced a feature that causes the iPhone to reboot every three days, security researchers have confirmed (via TechCrunch). In a demo video, security researcher Jiska Classen proved that an iPhone left untouched for 72 hours will automatically restart, and Graykey manufacturer also Magnet Forensics wrote a blog post about the feature.

After a reboot, an iPhone is more difficult to break into with the forensic tools used by law enforcement and others, such as bad actors. There are multiple unlocked states for an iPhone, and an iPhone that's at a passcode screen but has been previously unlocked with Face ID/Touch ID is easier to break into.

An iPhone that has recently restarted is in a "Before First Unlock" state, and that is when an iPhone is most secure because all data is encrypted. A reboot will initialize if a device is in a locked state (as in has been unlocked with Face ID or Touch ID but is now at the passcode screen) and has not been unlocked for a 72 hour period.

A 7-day inactivity reboot functionality was initially introduced in iOS 18, but the timer was shortened to three days with the launch of iOS 18.1. An iPhone in "Before First Unlock" state has messaging about Face ID/Touch ID being required after an iPhone restarts. An iPhone in the "After First Unlock" state simply says "Enter Passcode."

Apple has not provided details on inactivity reboot, and kept quiet about the addition of the feature. It was discovered when law enforcement officials noticed iPhones spontaneously rebooting following the launch of iOS 18. 404 Media last week shared a letter from officers in Detroit, Michigan, warning other law enforcement about the new limitation. While police speculated that the reboot could be tied to cellular network connectivity, iPhones will reboot regardless of connectivity status.

There was also speculation that an iPhone running iOS 18.1 could cause other iPhones to reboot, but that does not seem to be the case.

Law enforcement officials can still use brute force tools to get into iPhones running iOS 18 or later, but breaking into an iPhone must now be done before the iPhone restarts.

Article Link: iOS 18 Security Feature Causes iPhone to Reboot After Three Days of Inactivity

 

[N0ughtsAndCr0sses]

Unfortunately I’ll never use that feature 😂🤣🤙🏻

 

[Paddle1]

A bit annoying if you have devices laying around that need to be connected to Wi-Fi seeing as it gets disabled on a restart.

 

[1288261]

Aww bummer I guess Timmy lost his phone

 

[t0rqx]

This reeks rebranding a reboot bug into a feature. Like they did previously "introducing" hidden/deleted photos albums, when deleted photos were re-appearing.

 

[BarrettF77]

I hate this feature with a passion and the fact that there’s no way to turn it off irritates the hell out of me. Steve Jobs said you ask your customers for permission on things repeatedly, and this secretive nature of how they do business is becoming more and more irritating.

I get the used case and the value of it, but for devices that I don’t use as often it causes them to sit there and think for a while after I unlock it as a catch up on all of the messages and everything which is hugely annoying

 

[macguru212]

My car does the same thing.

 

[zapmymac]

Score a win for us consumers!

I do reboot my phone daily, and have for years. Why, because I’m just crazy 😬

 

[Sith_lord]

Not sure if it’s actually a feature or not. My iPhone 16 pro max reboots constantly especially when I am using it… I never ever let my phone go more a couple hours without using it.

 

[JosephAW]

Some of us don’t use touch or Face ID to unlock our devices but just a passcode.

 

[mknelson]

Unfortunately I’ll never use that feature 😂🤣🤙🏻

Why "Unfortunately"? Would you like the police to pick you up and seize your phone?

Weirdo!

 

[trip1ex]

Good for those in my line of work.

 

[JohnC1959]

This reeks rebranding a reboot bug into a feature. Like they did previously "introducing" hidden/deleted photos albums, when deleted photos were re-appearing.

Well, at least it's refreshing to have a bug that is highly predictable and is only seen if you have your phone sitting idle for four days.

 

[pradeepbabloo]

As long as Find My still works upon reboot, I dont think this will affect majority of the users. I do not really see how this would affect anyone, I could be wrong though. Are there any use cases that gets affected?

 

[breenmask]

imagine thinking iPhones have 72 hour battery life

 

[JohnC1959]

imagine thinking iPhones have 72 hour battery life

I suspect that for some of the scenarios they saw when adding this was one where the phone was plugged in the whole time.

 

[mongobongo]

Good for those in my line of work.

Drug dealer?

 

[godofredog]

I wish they let the user setup that feature to increase or decrease the time it takes to reboot when not in use. I think this is a great anti-theft feature to make it harder for the bastards to get into the phone's data. My iPhone was robbed in February 2024 and since then there have been thousands of login attempts into every single service that I use in my phone. They may have not been able to access all the information, but they managed to get hints of all the web pages and apps that I use and the login, username and/or email address (not the passwords as far as I can tell), specially online shopping sites and apps.

I would love to be able to setup my phone to reboot every 12 hours or so, I don't care waiting for a few munites to use my phone.

 

[tennisproha]

Can’t Before First Unlock also be triggered by activating and canceling an emergency call? I’ve read this is what you should be if law enforcement demand your phone.

 

[JPack]

Reminds me of Vision Pro, which shuts down after 24 hours of non-use.

Funny how a bad design/limitation on the VP is a good security measure on iPhone.

 

[DreadedFun]

I suspect that for some of the scenarios they saw when adding this was one where the phone was plugged in the whole time.

Yeah. Standard procedure for police is probably to connect the phone to power and turn off network/put in a radio shielded container, if they suspect that they need to get into a phone. Ready to be unlocked enten the lab have time.

 

[mongobongo]

I wish they let the user setup that feature to increase or decrease the time it takes to reboot when not in use. I think this is a great anti-theft feature to make it harder for the bastards to get into the phone's data. My iPhone was robbed in February 2024 and since then there have been thousands of login attempts into every single service that I use in my phone. They may have not been able to access all the information, but they managed to get hints of all the web pages and apps that I use and the login, username and/or email address (not the passwords as far as I can tell), specially online shopping sites and apps.

I would love to be able to setup my phone to reboot every 12 hours or so, I don't care waiting for a few munites to use my phone.

I agree! Except for when I'm sleeping I rarely go more than a few hours without unlocking my phone. Would like to set the time to 12 hours or temporarily even shorter than that. For example when travelling to areas where there is an elevated risk of theft, like Rio de Janeiro, to name just one example.

 

[mongobongo]

Can’t Before First Unlock also be triggered by activating and canceling an emergency call? I’ve read this is what you should be if law enforcement demand your phone.

Cancelling an emergency call doesn't do that, just tried it. I think what you might be referring to is pressing the side/power button 5 times repeatedly. This inactivates face id/touch id and requires you to enter the passcode manually to access the phone. However this is not the same as BFU, the phone is still in AFU even though it requires a passcode.

It's also something you can easily do as you are handing over your phone. As opposed to dialling an emergency call.

 

[BigBlur]

Can’t Before First Unlock also be triggered by activating and canceling an emergency call? I’ve read this is what you should be if law enforcement demand your phone.

I believe that was only to disable Touch ID/Face ID so that law enforcement can't force you to unlock it biometrically (or flash the phone in front of your face to unlock it). The phone remains connected to Wi-Fi and things remain loaded in memory when it's in this state.

 

[Student of Life]

Honestly this is great news. Personally i would like this time frame reduced To 24 hours or less.