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Cookie Stuffing; Not as Delicious As One Would Think

Posted on 9.11.2008
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Consider it one of the true plagues of doing business on the Web. Cookie Stuffing involves placing an affiliate tracking cookie on a website visitor's computer (often without their knowledge) which generates revenue (for the affiliate dropping the cookie) when the user visits the merchants site and makes a purchase, completes a lead form, etc. The problem for both hard-working affiliates and merchants alike is real and severely diminishes the genuine opportunity available in performance marketing.

This isn't just a passing fad; cookie stuffing is a major problem and has been one for quite some time. This issue demands your attention if you participate in affiliate programs or use an affiliate network as a merchant. Ebay has recently sued three affiliates for cookie stuffing and fraud committed through Commission Junction from 2003-2007. If you are dropping cookies, the good times may be coming to an end.

How Cookie Stuffing/Cookie Dropping Works:
Affiliate networks pay commissions or a revenue share to affiliates when conversions are generated on the merchants' site. Affiliates using "cookie-stuffing" or "cookie dropping" methods however mislead tracking systems to believe that a user has clicked through their tracking link (forcing them to pay commissions accordingly) even if the user has never actually clicked through the affiliate link. (Stuffing cookies usually comes in the form of a JavaScript code placed on a website, that simply opens a hidden version of another site in a 1by1 pixel box, which then installs the cookie from that hidden site in the browser - although others forms including iframes within forums are gaining traction.) If a user makes a purchase from that merchant immediately or before the cookie expiration date specified by the merchant's affiliate program expires -- the affiliate then receives a commission on the user's purchase.

Let's look at an example. Suppose a website visitor clicks to an affiliate site to read a review on a widget. This site does not use using cookie-stuffing, but the sales copy is so well written that the user is intrigued and clicks through the link to the merchant selling the widget. The user does not buy immediately but an authentic cookie has been placed on their machine so the affiliate gets credit for the purchase should one eventually take place. A few days later however, the user visits another affiliate site that is using cookie-stuffing and the same merchant site. Using cookie-stuffing, an affiliate tracking cookie on the second site overwrites the first sites cookie. If the user subsequently makes a purchase from the merchant selling the widget, the affiliate commission will be paid to the second affiliate, not the first, even though the first earned it and the second stole it.

Pretty shady, right? The worst part is that everyone except the affiliate dropping the cookie suffers. Cookie-stuffing has been effective in generating profits for affiliates that participate in the practice, but the effect on both merchants and honest affiliates is troubling. Cookie stuffing forces merchants to pay commissions to affiliates that never caused an actual user click-through. The ultimate result is that this could reduce the quality and effort of affiliates participating in the merchant's program.

Little has been published in the way of identifying affiliates that are engaged in cookie stuffing. In the future I am confident that affiliate network will begin tracking affiliates on the server side as a session variable as opposed to on the client side (machine). Website Magazine hopes to help the performance marketing industry change that by keeping a close eye on the trend and futures solutions within our Affiliate Insider newsletter.


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