Over the past several weeks, online tracking practices involving the use of Flash cookies and ETags have been the subject of new research studies, class action lawsuits and significant media attention.
- On July 29, 2011, a research team at the University of California, Berkeley, released a new study regarding Flash cookies (local shared objects) and HTML5 local storage and cache cookies via “ETags.” An ETag (or entity tag) is a cache control mechanism that can be used to store unique identifiers in a browser’s cache and track users even when cookies have been blocked and “private browsing mode” has been enabled. Unlike Flash cookies, which were the subject of the Berkeley team’s 2009 report, HTML5 storage does not require a plug-in, which the researchers suggest may make it a more universal tracking mechanism. The research team made 10 arbitrary clicks on each of Quantcast’s top 100 websites, collecting HTTP, HTML5 and Flash cookies during these “crawling sessions.” The study discussed the cookie “respawning” activity of two sites, and found that one of those sites used both Flash and cache respawning techniques to re-create HTTP and HTML5 cookies “in a way that cannot be blocked currently by the browser.” The researchers noted that “ETag tracking and respawning is particularly problematic because the technique generates unique tracking values even where the consumer blocks HTTP, Flash, and HTML5 cookies. In order to block this tracking, the user would have to clear the cache between each website visit.” In addition, the report indicated that websites that use KISSmetrics’ services could synchronize ETags to track users across domains.
- On August 18, 2011, a Stanford University report indicated that Microsoft has been using ETags capable of giving Microsoft “sufficient information to associate user interactions with [Microsoft] domains from before and after” a user clears her cookies. According to a Microsoft blog post, the company “quickly disabled” the code and confirmed that this functionality never caused Microsoft cookie identifiers or data associated with those identifiers to be shared with others outside of the company.
- On August 17, 2011, a federal court in New York dismissed some of the claims asserted against behavioral advertising network Interclick, and other advertisers, in connection with their allegedly deceptive tracking practices using Flash cookies. The suit had claimed violations of the Computer Fraud and Abuse Act (“CFAA”) and other federal, state and common law. The court dismissed the CFAA claims because the plaintiff failed to quantify any cognizable economic losses resulting from the allegedly deceptive tracking practices, which mirrors a California court’s April 28, 2011 dismissal of a similar suit that had been filed against Specific Media.