So it cuts power before the iPhone can store that a failed attempt occurred. It's such a simple, stupid, wonderful idea. I love it. Kudos to whoever came up with it.
This is not a particularly new attack. It's been used for years against simpler devices, especially where you can access the flash chip and force it's write protect on.
It's not really an "attack", but old Pokemon games on Gameboy and Gameboy Colour used the same technique for cloning items and pokemon - you send a pokemon to a friend, and switch off the power before the game has a chance to save successfully afterwards - presto, now both you and your friend have the sent pokemon.
Even on more modern Pokemon systems (nintendo DS) you could upload a pokemon to the cloud servers and watch the network traffic lights on your router. Shut off your DS as soon as your pokemon had been uploaded and when you start up your game again, the pokemon is still in your party. It's also in the cloud so you connect and pull your clone off the server.
Yep, there was a risk. But with pokemon games they would say "saving game now" but the actual process didn't start until the whole text appeared on the screen - so as soon as the letters started appearing you could kill the power and it was fine.
In high school we found one even better than that. If you unplugged the coke machine after choosing a soda but before it was delivered then it spit out the soda and still remembered your money when you plugged it back in. It's interesting to see that power off events are still mostly untested even on Apple devices.
We used to do the same thing in 9th grade. Eventually teachers had to go and supervise students who used a vending machine and only they had keys that would turn them on. I also used fake change from one of those "my first cash register" toys as a kid to buy pencils in elementary school. Those eventually got removed too haha.
