Premium websites are equally vulnerable to the fraud.
A big portion of the amount spent on digital advertising goes into the hands of cyber criminals, with 23% of video ads and 11% of display ads viewed by fake consumers.
The findings were revealed during a study by the Association of National Advertisers (ANA) and security firm White Ops, who analysed 181 campaigns from 36 ANA member companies to determine bot fraud. The fraud consists of automated entities that replicate the behavior of humans that click and view ads.
The study measured 5.5 billion impressions in 3 million domains over 60 days, in line with industry spending patterns.
The study found that the bots were capable of setting up fake websites and delivering fake audiences to make use of third-party traffic, taking money away from brands which could amount to up to $6.3bn in 2015.
During the study, it was also found that botnet controllers hijacked consumer identities through home machines to get away with ad fraud.
Previously, it was considered that low-price ads were the prime target of bot fraud, but the study revealed that premium websites and publishers were equally vulnerable.
White Ops CEO Michael Tiffany said: "It’s about stopping outright criminal theft."
"Ad fraud is hugely profitable and is one of the major sources of funding for a global underground responsible for a broad spectrum of cybercrime."
"To protect this cash cow, adversaries are aggressive, smart and adaptable. As such, the results of this study should not be about building better mousetraps, but about driving substantive change in the industry to alter the economics for criminals, and ultimately drive them out of business."
ANA has suggested advertisers and publishers advertise during waking hours as bot frauds were mostly active when users are asleep.