'Fingerprinting' tool challenges privacy safeguards for federal websites
The difficulty of maintaining user anonymity in the face of canvas fingerprinting poses a challenge to agencies trying to adhere to privacy standards set by OMB.
A recently discovered tool for tracking computer identities could threaten the privacy of visitors to thousands of popular websites, including dozens of federal sites.
"Canvas fingerprinting" is a new form of browser tracking that, as of early May, researchers from Princeton University and Belgium's KU Leuven University estimate had affected 5 percent of the world's 100,000 most popular websites. The tracking mechanism uses a web browser's application programming interface (API) to "draw invisible images and extract a persistent, long-term fingerprint without the user's knowledge," the researchers wrote in the draft of a forthcoming paper. The online news site Mashable reported on the research July 21.
The tracking tool has latched onto the websites of the departments of Homeland Security and Commerce, the White House and the Social Security Administration, among several other federal sites.
An online widget developer called AddThis wrote most of the fingerprinting code that appears on the affected websites. AddThis CEO Rich Harris told Mashable that his firm is exploring canvas fingerprinting as an alternative to "cookies," the more common user-tracking tool.
The difficulty of maintaining user anonymity in the face of canvas fingerprinting poses a challenge to government websites trying to adhere to privacy standards set by the Office of Management and Budget.
Affected agencies have been working to address privacy concerns since last month's revelation of canvas fingerprinting and its inclusion in the AddThis code. Most agencies contacted for comment by FCW deferred to the White House, which, as of this writing, had yet to respond. [UPDATE: A White House spokesman contacted FCW on Aug. 5 to say that the canvas fingerprinting code had been removed from WhiteHouse.gov.]
The Transportation Security Administration, a component of DHS, said it planned to remove the AddThis widget from its website Aug. 5. "The canvas fingerprinting was implemented via the 'AddThis' capability as an inherent feature unbeknownst to TSA. TSA was not using the canvas fingerprinting capability," the agency said in a statement to FCW.
Though the General Services Administration's website was not one of those listed by researchers as affected by canvas fingerprinting, an agency spokeswoman said GSA had negotiated its terms of service with AddThis years ago and was reviewing the matter.