According to Click Forensics, 42.6 percent of fraudulent clicks came from botnet-infected computers, the highest rate in four years, reports Computerworld. Botnets accounted for 27.5 percent of bad clicks a year ago.
It's not clear how much this costs advertisers or publishers. The last quarter showed that overall.14.1 percent of the clicks on ads were bogus.
Fraudsters are getting more sophisticated, with the latest trick being to let the botnet's computers click on ads across a high number of computers with a low frequency, making the traffic look as real as possible.