[patrickfl]

very thorough article - I've always wanted to know how these worked. I had no idea that many of them used Bluetooth / serial etc.

One revision to the post I'd like to see - I'd love to see a section on how they attach to the actual reader. I know they mentioned MitM attacks, but do these readers fit over the top of the skimmer? underneath? behind the entire skimmer? are the visible from the pump itself?

[m1n1]

They open the pump face, unplug the back of the existing reader, plug the front of their skimmer into the back of the existing reader, and connect the first plug into the back of their skimmer.

It goes from ? --> reader

to

? --> skimmer --> reader

The face of the pump appears unchanged (unless they broke a security sticker and were unable to replace it)