We recently uncovered elaborate advertising fraud activity on over 1,200 suspected websites that are costing online advertisers an estimated $6.8 million per month. This massive fraud originated from user traffic on websites classified as copyright infringement. The ad impressions from this traffic were ‘laundered’ through a complex series of redirects that make the ads appear as though they originated on legitimate sites containing advertiser-friendly content. Further, the fraudulent ads use code hiding the ad creative from being displayed in the user’s browser, resulting in advertisers paying for impressions that are never seen.