People have possibly been hacking 'space objects' for well over two decades, but (understandably) not much of that is in cited journals. The most you hear about it is that someone knows someone who knows someone that did something, in very rare cases the someone that did something even has a name.

That's not exactly verification, but there is so much smoke around this subject it would be hard to imagine there are no sparks or even a small fire.

Hacking a space borne piece of hardware that is in active use is probably an excellent way to become a 'person of interest' for a ton of agencies that you want no interaction with whatsoever. If you see an E2 flying in your neighbourhood while you're doing this it might be time to start packing.