User blog:Niik40/Modders

So I was playing search and destroy today on mw2, and this guy somehow was firing his Fal in fully automatic mode. I understand this is because they're cheating the game somehow, but not much else. my questions are: A:How? B:Why aren't they getting banned for it? This is also a major problem with the leaderboards, people hack their way to the top and it's really obvious, yet it stays like that and they never get banned or anything.