How does Black Ops 2 detect hacks?

Basically the title says it all, do they find cheaters by going over demos of players that have been reported? Or do they detect changes in the games memory? :S

- Boots.

From what I know, vac goes first, and when it doesn't detect anything, then treyarch scans through demos for suspicious behavior.

Not true,from what i heard treyarch scans your computer while you play blackops2

Trey does scan, and no its not illegal its in the TOS you agreed to :P

We will never know the actual process and I doubt that Treyarch will release such information willingly.