Researcher reveals how iPhone’s ‘Inactivity Restart’ feature works
iOS 18.1 was rolled out to users last month with a new security feature that can restart a user’s smartphone if it has not been unlocked for three days, effectively protecting the data on the device from thieves, according to security experts who tested the feature. A recent report found that iPhone units seized for forensics were restarting on their own, and it was later revealed that the ‘inactivity restart’ functionality had been added as part of the latest iOS update.
How Apple’s ‘Inactivity Reboot’ works on an iPhone
Last week, security researcher Jiska Classen said revealed that Apple had added a new feature called ‘Inactivity Reboot’, which would cause an unattended iPhone to restart after a certain period of time. The researcher has now revealed that the feature will activate after three days, along with a demonstration of how it works.
See the latest iOS idle restart in action!
iOS 18 comes with improved anti-theft measures. Three days without unlocking, the iPhone will restart so thieves can’t get hold of your data. (1/4) pic.twitter.com/H24Tfo1cSr
— Jiska (@naehrdine) November 13, 2024
In a video on The security feature is designed to limit unauthorized access to a smartphone when it is not actively in use.
When an iPhone restarts, it enters a state called ‘Before First Unlock’ (BFU). This is when the encryption keys used to protect user data are deleted. safely stored on the handset’s chipset, in a secure subsystem called the Safe enclave.
It is much more difficult for someone to gain unauthorized access to the smartphone in BFU status, compared to ‘After First Unlock’ (AFU), which, as the name suggests, is when the phone is unlocked, and biometric authentication (Face ID or Touch ID) is enabled.
However, the researcher warns that three days (in AFU state) is enough time for law enforcement agencies to access user data, especially if they use professional tools or experts. However, thieves can gain access to an iPhone using outdated tools.
Users can also enable Stolen Data Protection – a feature introduced in iOS 17.3 – which prompts the use of biometric authentication to change important settings on an iPhone. This feature is disabled by default as it adds more friction to the process of changing some settings, but users will reportedly be asked to enable it when setting up their iPhone with the upcoming iOS 18.2 update.
