What is cookie stuffing?
Cookie stuffing is an affiliate-marketing fraud where a website or extension secretly drops affiliate tracking cookies on a visitor's browser without them clicking any link. If the person later buys from that retailer on their own, the fraudster's cookie claims the sale, and the retailer pays a commission for a purchase the affiliate did nothing to cause.
Cookie stuffing exploits how affiliate marketing programmes credit the last affiliate cookie before a purchase. Techniques include invisible iframes or images that load affiliate links, pop-unders, and browser extensions that rewrite links or inject codes at checkout. It is a form of attribution fraud.
Merchants detect it by looking at affiliates whose clicks have abnormally short or zero time before purchase, very high conversion rates from little traffic, or sales concentrated among existing loyal customers. Affiliate networks can ban publishers and withhold commissions. Browser extensions that swap in their own affiliate codes have drawn public scrutiny and lawsuits.