[lelanthran]

> I believe breached PoS terminals were what happened in the big Target hack.

The problem is that PoS terminals are not EMV terminals. EMV terminals have been through a certification process, and the hardware part of that certification ensures that the vendor only runs signed-binaries.

Honestly, even if you could write and sideload (or even replace) the applications on the EMV terminal, I do not see a way to get them to a) run, and then b) send money elsewhere.