Most users rarely shut down or restart their iPhones. However, a newly discovered, unannounced security feature in iOS 18 allows iPhones to restart automatically after a period of inactivity. This feature appears to be aimed at deterring unauthorized access, particularly from bad actors like thieves.
Last week, reports emerged that U.S. law enforcement agencies had issued alerts about an unexpected matter: iPhones being held for forensic examination were rebooting on their own. A subsequent investigation by 404Media linked this behavior to the new “inactivity reboot” feature introduced in iOS 18.
iPhones Now Auto-Reboot After 72 Hours of Inactivity
Security researcher Jiska Classen has since provided further insights into this feature. According to published findings of Classen, an iPhone running iOS 18.1 will automatically reboot if it remains in a locked state and is not unlocked for 72 hours.
This marks a change from the initial version of the feature in iOS 18, where the inactivity timer was set to seven days. Apple has not mentioned this functionality in its iOS 18 release notes, suggesting that it has been quietly introduced and refined in iOS 18.1.
Why Does Apple Force Reboot Inactive iPhones?
The primary goal of this feature is to make it significantly harder for unauthorized entities to break into an iPhone and access its data.
When an iPhone reboots, it enters a “before first unlock” state. In this state, encryption keys are locked, and biometric authentication (such as Face ID or Touch ID) is required to regain access. This additional layer of security makes it more difficult for conventional forensic tools to bypass the device’s protections compared to a standard locked screen.
However, Classen points out that while the iPhone can still be unlocked in this state, doing so requires advanced tools, extensive expertise, and considerable effort—making unauthorized access far more challenging.
The inactivity reboot aligns with Apple’s broader push to enhance iPhone security. Earlier this year, the company introduced Stolen Device Protection, a feature designed to make it even harder for thieves to access stolen iPhones, particularly those with compromised passcodes.
What are your thoughts on Apple’s new inactivity reboot feature and its ongoing efforts to bolster device security? Please let us know your opinions in the comments below!