Shady 'Merry-Go-Round' Ad Fraud Network Leaves Orgs Hemorrhaging Cash

Researchers uncovered the "Merry-Go-Round" ad-fraud rings that invisibly overlay low-reputation websites to spawn pop-under windows which cycle domains and load large numbers of ads (peaking at ~782 million ads/day, currently ~200M/day). The operation uses anti-detection techniques—cloaking, referrer resetting, and noindex directives—to hide from crawlers and investigators, causing substantial financial losses to advertisers; mitigation recommended is to reduce reliance on intermediary ad exchanges and buy inventory from known partners.