Adsense and other networks have been used for this kind of thing for a long time. I consulted for a company a few years ago that was losing ~$100K/mo through a

Adsense and other networks have been used for this kind of thing for a long time. I consulted for a company a few years ago that was losing ~$100K/mo through a similar technique. They happened to use Adsense on their pages, and also had an affiliate program. Rogue affiliates would display an ad through Adsense targeted only to their site, and use a flash banner that surreptitiously loaded their affiliate cookie for the site onto the user's browser after they were already there. The site would then dutifully pay commission on all of these sales, even though the affiliate had nothing to do with getting the user there. I helped identify and plug this gaping hole in their profits. Ad networks really need to take more responsibility to monitor both landing pages and the ads themselves more carefully. Enabling drive-by malware installs, affiliate fraud, and all other manner of schemes - even unwittingly - is bad for everyone involved.