Uncovered by digital advertising security firm White Ops, the “Methbot” operation, a variation on the botnet, uses a vast network of “cloaked Internet addresses, rented data centres, phone Web sites and fake users” to simulate real people viewing ads online, Brian Krebs reported.

Typically ad fraud takes place from computers and servers infected with malicious software. Instead, “Methbot” network runs on a distributed network of dedicated Web severs and computers.

According to the New York Times, the fraud started in September and is still ongoing. It has been traced to Russia, where it is believed that a criminal organisation uses it to make money.