New Apple security feature reboots iPhones after 3 days, researchers confirm

How they know it’s an intentional feature

• Logs explicitly show an “inactivity reboot” entry, and researchers mention reverse engineering, so commenters reject the “maybe it’s a memory leak” idea.
• Security Research Devices show verbose boot logs, but that level of output isn’t expected on normal devices.

What the feature does and when it triggers

• iOS 18 reboots an iPhone if it hasn’t been successfully unlocked for ~72 hours.
• Several commenters note this puts the device into a more secure “before first unlock” (BFU) state where user data is still encrypted.
• Some point out it only affects phones unused for days, so most users may never notice.

Configurability, UX, and threat models

• Many want the timeout configurable, e.g. 8–24 hours, or even 30 minutes; others argue 72 hours is a cautious first rollout to avoid user complaints.
• Several suggest tying shorter timeouts to Lockdown Mode, MDM, or Apple Configurator rather than a visible consumer setting.
• Some worry about missed calls/notifications during reboots, others already accept PIN-only workflows due to legal or police threats and would tolerate frequent reboots.
• There’s debate over how usable the phone is post‑reboot before unlock: some say no network/notifications, others report their Android phones are usable.

Shortcuts and automation attempts

• Users try to emulate shorter timeouts via Shortcuts scheduled reboots, but iOS generally prompts for confirmation, defeating unattended automation.
• Some report “Run immediately” works without prompts; others say it doesn’t, possibly device/iOS-version dependent. Overall behavior is described as buggy and limited.

Comparisons to GrapheneOS and Android

• GrapheneOS already has a configurable “auto-reboot after inactivity” (default ~18 hours) and is praised for broader security features.
• Samsung and Pixel devices offer scheduled reboots, but commenters note those are often for performance, and on some devices auto‑reboot appears less “full” (notifications work without unlock).
• Some see Apple’s move as catching up to practices in hardened OSes and PCI‑regulated payment terminals, especially as iPhones increasingly act as POS devices.

Security philosophy and tradeoffs

• Reboots are framed as defense‑in‑depth: clearing in‑memory exploits like spyware.
• Others stress UX and legal realities: stronger technical protections mainly help where due process works; they don’t stop coercive attacks.