Guy had no idea what the attack -- if any -- was. All he noticed was odd activity on his account, which as easily could have been human error at Google. Howeve

Guy had no idea what the attack -- if any -- was. All he noticed was odd activity on his account, which as easily could have been human error at Google. However as to his point that this is a massive imperilment of Google : Not really. Google ads run on a bid system, so introducing fake money doesn't actually reduce the amount of money Google actually makes, and may actually increase it. I get $100+ AdWord credit offers from Google literally monthly, because the effect of my credit is only that I push up the cost for everyone else. Obviously there are limits to this (when advertisers simply bow up) but unless the fraud was really widespread it wouldn't damage Google.