I used to just DDOS people’s AIM and messengers if they crossed me, as a phantom curse attached to them and they had no idea the cause.

I would chat with them as normal at the same time, chuckling to myself as they kept falling offline following a barrage of emoticons and requests from my army of chat bots that made their process run out of memory.

Eventually I’d bore of it. Or have one of the chatbots tell them not to cross someone again. In your scenario I probably would have said it was the person he got the exploit from, instead of making a link to someone I care about.