Computerworld reports that in the third quarter, more than 20 percent of clicks on pay-per-click ads were unintended or malicious. The article explains:
Click fraud occurs when PPC ads are clicked on either by mistake or maliciously. Errant clicks happen when users unintentionally click on an ad. The malicious clicks usually come from Web publishers seeking to drive up their PPC ad commissions.
Click Forensics attributes the increase to automated attacks launched using botnets and on new ad sources that fraudsters are exploiting, like mobile, social networks and video.
The company found similar results in the first quarter of this year when it reported that the click fraud rate for the first quarter of 2010 was one of the highest on record. Again, the blame was placed on botnets.