Before 2011, it was thought that the problem of online advertising fraud was more or less contained. Pay-per-click advertising was still experiencing huge growth, but much of the fraud activity and many of the practices had been seen and countered.

Google themselves have long since acknowledged the need to clamp down on fraud. Google is a business like any other; people need to trust them. For instance, they knew that if they failed to detect click-through fraud, then advertisers would lose faith in their brand. There’s nothing quite like a potential drop in profits to kick-start a company into taking action.

Bots, click farms and the like were treated as a priority for the company. And for good reason. Google used experts like Professor Alexander Tuzhilin to draw up best practices for preventing click fraud and things seemed to be working.

But things took a turn for the worse in 2011, when two infamous source-code leaks gave access to malware to all and sundry. Whereas before, only a few people had the capability to exploit online advertising campaigns, the upshot of the leak was that it allowed less technically-savvy people to hijack PCs, phones and tables.

And as we stand today, the uninitiated criminal can set up a bot for around $500 and they don’t need to know the first thing about coding. Such is the extent of the issue, cybercrime is already more profitable than drug dealing and that trend is only set to continue.

Here are some numbers to illustrate the point. It’s thought that over 30% of the total number of PCs in the US and Worldwide are hijacked. So you only need to think about the amount of content served up on those PCs to calculate that there’s a lot of advertising reaching the wrong eyes.

These facts are only scratching the surface, but there are things you can do to counter the issue.