An ad fraud botnet is a distributed network of computers controlled by a botmaster to defraud advertisers.
Usually, a botnet is made up of computers that are infected with malware and co-opted without the knowledge of the owners. An alternative model often involves dedicated servers running in rented data centers. While a botnet based on compromised computers is quick to assemble and cheap to run, the custom-built model can be much more effective and reliable.
In late 2016, White Ops, an advertising security vendor, reported that an ad fraud botnet campaign they called Methbot was generating approximately 300 million fake ad views a day and charging advertisers three cents per view, for a daily profit estimated at somewhere between $3 million and $5 million. The botnet comprised a distributed network of dedicated servers and computers in rented facilities in the United States and the Netherlands. The scammers cloaked the IP addresses of machines and created fake websites to host video ads. They used software to replicate the behavior of users watching the ads, simulating clicks and forging social media login data to appear convincing.
According to Ad Week, ad fraud costs the advertising industry over $7 billion per year globally.