Computer hackers are a sophisticated system of fake websites and artificial web users to deceive advertisers into thinking that people are clicking on billions of online adverts and videos every day.
The fraudsters create a series of fake websites and use computer programs called "bots" to record the starting and stopping of videos and clicks on adverts, which are then reported to advertising companies as activity by humans on real websites.
In fact, some experts believe that 70% of online advertisements are never even watched or clicked by humans.
This statistic stunned Ron Amram, vice-president of media at Heineken USA, who admitted to Bloomberg in 2014, "It was like we'd been throwing our money to the mob."
Cybersecurity expert Augustine Fou insists that hackers are getting away with the fraudulent activity because of a lack of attention paid towards the ad networks, allowing bots to freely operate at a "rampant" level.
"Bots are rampant and ad fraud is at its highest ever point," said Augustine Fou, a cybersecurity expert, speaking to the Times. "They are creating fake websites and adding them by the thousands to the ad networks and no one checks. The whole digital ecosystem is a house of cards built on fake metrics."
He added that advert networks were "making it easy for fraud to happen".
The hackers make themselves an attractive proposition to advertisers with their combination of fake users and fake websites, amassing a search history that in Fou's opinion, would force potential suitors to do business with them due to the fast money-making nature of the advertising industry.
"Real publishers see lower revenue and advertisers get hurt because their ads don't reach customers, but everyone in the digital supply chain makes money hand over fist."
The Association of National Advertisers claims that $7bn (£5.5bn) was lost to fraudsters in January and, White Ops digital security operators that expose bot fraud, discovered one network that had 500,000 adverts pumped into it.
Google is currently leading the fight against bot fraud, hiring 100 employees to hunt down and remove fraudulent ads. In 2016 they took down 1.7m suspect adverts.