Authors:
Libor Polčák
1
;
Marek Saloň
1
;
Giorgio Maone
2
;
Radek Hranický
1
and
Michael McMahon
3
Affiliations:
1
Brno University of Technnology, Faculty of Information Technology, Božetěchova 2, 612 66 Brno, Czech Republic
;
2
Hackademix, via Mario Rapisardi 53, 90144 Palermo, Italy
;
3
Free Software Foundation, 51 Franklin Street Fifth Floor, MA 02110 Boston, U.S.A.
Keyword(s):
Browser Fingerprinting, Web Privacy, Web Security, Webextension APIs, JavaScript.
Abstract:
The web is used daily by billions. Even so, users are not protected from many threats by default. This paper builds on previous web privacy and security research and introduces JShelter, a webextension that fights to return the browser to users. Moreover, we introduce a library helping with common webextension development tasks and fixing loopholes. JShelter focuses on fingerprinting prevention, limitations of rich web APIs, prevention of attacks connected to timing, and learning information about the device, the browser, the user, and the surrounding physical environment and location. During the research of sensor APIs, we discovered a loophole in the sensor timestamps that lets any page observe the device boot time if sensor APIs are enabled in Chromium-based browsers. JShelter provides a fingerprinting report and other feedback that can be used by future web privacy research. Thousands of users around the world use the webextension every day.