That seems a very good question to me and my own answer is - I haven't a clue.
I received a very nice e-mail from a digital forensics technologist in Iran (whose name I won't reveal for obvious reasons) who seems as concerned as I am about the blurred legal lines that surround state-sponsored hacking.
The U.S. has pointed accusing fingers at China and of course it now turns out that the U.S. and Israel have also engaged in state-sponsored hacking. No doubt Iran is doing the same thing though my correspondent made no reference to that.
Even India is reportedly getting into the game - and a dangerous game it is.
So if any RTL readers know more about international law on this subject than I do, please provide illumination and I'll post what I learn.