The Hardware Exploit Vector
By default, if an iPhone has been locked for less than an hour, the lightning or USB-C port remains fully active for data transmission. This means malicious actors or law enforcement agencies can plug specialized forensic extraction tools (like GrayKey or Cellebrite hardware) directly into the locked phone and begin aggressively attempting to bypass the passcode via the USB protocol. To secure your device against physical, hardware-based brute-force attacks, you must permanently restrict the physical port to power-delivery only.
How to Disable USB Accessories on the Lock Screen
You can permanently secure the physical data port via the Face ID & Passcode settings.
- Open the Settings app on your iPhone.
- Scroll down and tap on Face ID & Passcode (or Touch ID & Passcode).
- Enter your strict device passcode to authenticate.
- Scroll down to the section labeled “Allow Access When Locked.”
- Locate the toggle switch labeled Accessories (or USB Accessories).
- Toggle this switch to the Off position (the green background will disappear).
A Hardened Physical Perimeter
The change takes effect instantly. The iPhone will completely sever the internal data bridge connecting the physical charging port to the iOS file system whenever the device is locked. If you plug a USB flash drive, a computer, or a malicious cracking tool into the phone, the operating system will absolutely refuse to establish a data connection. The port will strictly accept electrical current for charging. To transfer data or sync with a computer, you are now strictly required to unlock the phone via Face ID first, guaranteeing absolute hardware isolation.