I've always wondered what these electronic billboards run on. Obviously I'm not going to cut one down and bring it home to study nor will I impersonate a customer to get one, so I'll never find out, but it's cool someone did manage to hack one.

It's just a computer running windows + big screen + app in full-screen mode that show the images/videos on a loop and can be controlled from a central server

Some version of Windows + custom software

There are a surprising number of Linux thing running webstuff likely hacked together and shipped. I find a lot of vending machine computers on eBay that boot Ubuntu or whatever and start some sort of webservice thing.

What custom software though? How does it get the data? What is it vulnerable to? What about the backend software, that's also part of the system? It's easy to say "it is hardware running software" but it obviously goes deeper than that.

I mean the easiest step would be finding someone that works with the software installing them and see if they like to talk.

If you're the kind of person that's good at making relationships you might even talk them out of old or dead hardware.

How would you find someone?

Hopes, dreams and FM.