Posts Tagged ‘BFU’

DFU Mode Cheat Sheet

January 14th, 2021 by Oleg Afonin

The Device Firmware Upgrade mode, or simply DFU, just got a second breath. The ability to image the file system, decrypt the keychain and even do passcode unlocks on some older iPhone models has been made possible thanks to the checkm8 exploit and the checkra1n jailbreak, both of which require switching the phone into DFU. The procedure is undocumented, and the steps are different for the various devices.

The USB restricted mode was introduced in iOS 11.4.1, improved in iOS 12 and further strengthened in iOS 13. The USB restrictions are a real headache for iPhone investigators. We’ve discovered a simple yet effective trick to fool it in some cases, but currently it securely protects the iPhones from passcode cracking and BFU (Before First Unlock) extractions. However, there is a trick allowing you to obtain some information from devices with disabled USB interface. Learn how to use this trick with the recently updated iOS Forensic Toolkit.

We have recently updated Elcomsoft iOS Forensic Toolkit, adding the ability to acquire the file system from a wide range of iOS devices. The supported devices include models ranging from the iPhone 5s through the iPhone X regardless of the iOS version; more on that in iOS Device Acquisition with checkra1n Jailbreak. In today’s update (for both Windows and macOS platforms as usual), we’ve added the ability to extract select keychain records in the BFU (Before First Unlock) mode. We have a few other changes and some tips on extracting locked and disabled devices.