That is a great question that I don't have an answer for. It is evident that IW has failed to create a anti-cheat in this game and not sure what you or I can do if we join a game and realize it is a "Hacked" server so to speak and receive temporary rewards. Obviously if you know the server is not Legit then leave immediately. I am not sure how a real gaming company would handle this as IW has failed to address the "Hacking" or "Cheating" in this game.
Great question again, but since IW does not respond to these threads I don't have an answer. Anyone else out there have a comment or suggestion?