Botnets Behind One Fourth of Click Fraud

First the good news: Click fraud dropped ever-so slightly last quarter, from 16.3 percent to 16.2 percent. But the bad news is that botnets were the force behind over 25 percent of all click fraud traffic in the second quarter, according to the latest numbers on pay-per-click fraud reported in the Click Fraud Index.

The numbers -- logged by the Click Fraud Network, a group over 4,000 online advertisers and ad agencies and reported by Click Forensics -- also revealed a slight decrease in the average number of fraudulent pay-per-click ads found in search engines such as Google AdSense and Yahoo Publisher Network. The average for the second quarter was 27.6 percent, down from 27.8 percent in the first quarter.

But the big red flag in the report was the increasingly automated nature of click fraud, with botnets pumping out an average of one fourth of all such fraud in the second quarter. "Although click fraud rates were relatively unchanged in the second quarter, we found that the methods used to commit click fraud have become increasingly more sophisticated and difficult to detect," said Tom Cuthbert, president of Click Forensics. "The threat from botnets is the biggest concern as they have grown to cause over one quarter of all click fraud. Online advertisers should be extra vigilant in watching for traffic from botnets in their search marketing campaigns."

Danny McPherson, director of security research for Arbor Networks, says he's not surprised by the latest botnet numbers. "I know many of the core content folks are quite concerned with bits and click fraud, and suspect there is a great deal more abuse there then folks actually realize...it's extremely hard to detect if done right." McPherson says.

Meanwhile, China, Russia, and France were the main hotspots for orchestrating click fraud outside of North America, according to the Click Fraud Index, with 4.3 percent coming from China, 3.5 percent from Russia, and 3.2 percent from France.

— Kelly Jackson Higgins, Senior Editor, Dark Reading