Privacy & Information Security Law Blog

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 1, 2011, a class action complaint was filed in a federal court in California against Space Pencil, Inc., d/b/a KISSmetrics, and more than two dozen websites that used KISSmetrics’ services.  The suit alleges the defendants violated the federal Wiretap Act and California state law by using online tracking techniques such as browser cache, HTML5 storage and Flash cookies that can circumvent browser privacy controls.  According to the complaint, the defendants used KISSmetrics technology to re-create tracking cookies that users had deleted.  The plaintiffs allege that “while it is generally reasonable to expect a website to use cookies for tracking,” the defendants created “numerous, alternative, ‘shadow’ mechanisms for tracking,” exploiting plaintiffs’ browsers and other software “in ways that consumers did not reasonably expect.”  The complaint also asserts that the defendants’ tracking practices enabled them to acquire plaintiffs’ personal information without authorization, thus “depriving [plaintiffs] of the opportunity to exchange their valuable information for the content and services of websites” that met the plaintiffs’ reasonable privacy expectations.  According to reports, two of the named defendants suspended their use of KISSmetrics after it was revealed that the company had been using ETags to track consumers online.
• 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 included other federal, state and common law claims.  The court dismissed the CFAA claim 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.