Stealthy Web tracking tools pose increasing privacy risks to users

The use of such tracking tools may be unknown to most users, according to a research paper

Three stealthy tracking mechanisms designed to avoid weaknesses in browser cookies pose potential privacy risks to Internet users, a new research paper has concluded.

The methods -- known as canvas fingerprinting, evercookies and cookie syncing -- are in use across a range of popular websites. The findings, first reported by Pro Publica, show how such tracking is important for targeted advertising but that the privacy risks may be unknown to all but the most sophisticated web users.

Profiling Web users, such as knowing what Web pages a person has visited before, is a central component of targeted advertising, which matches advertisements with topics a person may be interested in. It is key to charging higher rates for advertisements.

Cookies, or data files stored by a browser, have long been used for tracking, but cookies can be easily blocked or deleted, which diminishes their usefulness.

The methods studied by the researchers are designed to enable more persistent tracking but raise questions over whether people are aware of how much data is being collected.

The researchers, from KU Lueven in Belgium and Princeton University, wrote in their paper that they hope the findings will lead to better defenses and increased accountability "for companies deploying exotic tracking techniques."

"The tracking mechanisms we study are advanced in that they are hard to control, hard to detect and resilient to blocking or removing," they wrote.

Although the tracking methods have been known about for some time, the researchers showed how the methods are increasingly being used on top-tier, highly trafficked websites.

One of the techniques, called canvas fingerprinting, involves using a Web browser's canvas API to draw an invisible image and extract a "fingerprint" of a person's computer.

It was thought canvas fingerprinting, first presented in a research paper in 2012, was not in use on websites. But it is now employed on more than 5,000 of the top 100,000 websites ranked by metrics company Alexa, according to the paper.

More than 95 percent of those canvas fingerprinting scripts came from, a company that specializes in online advertising, content and web tracking tools. could not immediately be reached for comment.

The researchers also found some top websites using a method called "respawning," where technologies such as Adobe System's Flash multimedia program are manipulated to replace cookies that may have been deleted.

These "evercookies" are "an extremely resilient tracking mechanism, and have been found to be used by many popular sites to circumvent deliberate user actions," the researchers wrote on a website that summarized their findings. Respawning Flash cookies were found on 107 of the top 10,000 sites.

The third method, cookie syncing, involves domains that share pseudonymous IDs associated with a user. The practice is also known as cookie matching and is a workaround for the same-origin policy, a security measure that prevents sites from directly reading each other's cookies. Such matching is helpful for targeting advertisements and for selling those ads in automated online auctions.

The researchers argue that cookie syncing "can greatly amplify privacy breaches" since companies could merge their databases containing the browsing histories of users they're monitoring. Such sharing would be hidden from public view.

Those companies are then in "position to merge their database entries corresponding to a particular user, thereby reconstructing a larger fraction of the user's browsing patterns."

"All of this argues that greater oversight over online tracking is becoming ever more necessary," they wrote.

The paper was authored by Gunes Acar, Christian Eubank, Steven Englehardt, Marc Juarez, Arvind Narayanan and Claudia Diaz.

Send news tips and comments to Follow me on Twitter: @jeremy_kirk

Join the CSO newsletter!

Error: Please check your email address.

Tags analyticsadvertisingInternet-based applications and servicessecurityinternetdata

More about Adobe SystemsAustralian Pharmaceutical Industries

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jeremy Kirk

Latest Videos

  • 150x50

    CSO Webinar: Will your data protection strategy be enough when disaster strikes?

    Speakers: - Paul O’Connor, Engagement leader - Performance Audit Group, Victorian Auditor-General’s Office (VAGO) - Nigel Phair, Managing Director, Centre for Internet Safety - Joshua Stenhouse, Technical Evangelist, Zerto - Anthony Caruana, CSO MC & Moderator

    Play Video

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

More videos

Blog Posts

Market Place