[mrguyorama]

>Such machines just run a single app that comes from the factory, and aren't use for general computing.

And those machines are always running a purpose built program made by the lowest bidder and have TRIVIAL flaws to exploit.

The malware got in the same way malware got into Windows 2000 back in the day: the code exposed to the network is trash and is full of holes you can drive a truck through.