Data Acquisition from iOS Devices - Practical Mobile Forensics - page 79

6. Release the Power button and continue to hold down the Home button until you
are alerted by iTunes with the iTunes has detected an iPhone in recovery mode.
You must restore the iPhone before it can be used with iTunes message.
7. At this point, the iPhone screen will be black and should not display anything.
The iPhone is ready to be used in DFU mode. If you see the Apple logo or other
signals that the device is booting, repeat steps 2 through 6 until iTunes displays
that message.
To verify whether the iPhone is in DFU mode on Mac OS X, launch System Information
and go to the USB option. You should see a device similar to what is shown in the follow-
ing screenshot:
The MAC system information displaying a DFU-mode device
Just like in recovery mode, to exit DFU mode, hold down the Home button and the Power
button until the Apple logo appears on the device. More information can be found on
methods to verify DFU mode at http://www.zdziarski.com/blog/wp-content/uploads/2013/
05/iOS-Forensic-Investigative-Methods.pdf .