A sprawling new adware campaign that abused the Vast video ad server template to rack up fraudulent digital advertising views on an enormous scale has been shut down.

At its peak, the adware effort hit more than 12 billion requests per day.

Human Security’s Satori threat intelligence team uncovered the adware campaign, touting it as the largest find in the cybersecurity research group’s history. Following the discovery, Satori said it led a takedown of the ad fraud operation, which they dubbed as Vastflux.

The team added in its report that, in all, Vastflux spoofed more than 1,700 apps, targeted 1,200 publishers, and displayed ads on applications running on about 11 million devices.

“What was technically impressive and incredibly concerning about Vastflux [were] the fraudsters hijacked impressions on legitimate apps, which makes it nearly impossible for users to tell if they are impacted,” Gavin Reid, Human’s CISO, said.