With the news of Google and others getting hacked, I was wondering how companies find out, detect, and/or know they've been hacked in the first place?
Sure, if they find a virus/trojan on user's computers or see a very high access rate to parts of their system that don't usually see much, if any, traffic. But, from what I've see in articles, the attack was pretty 'sophisticated', so I wouldn't imagine the hackers would make it so obvious of their hacking in the first place.
Maybe someone can enlighten me on current detection schemes/heuristics. Thanks.