JShelter: Give Me My Browser Back

TL;DR

JShelter is a browser extension designed to enhance user privacy by preventing fingerprinting, limiting web API misuse, and blocking timing and sensor-based attacks, thereby empowering users against various online threats.

Contribution

It introduces JShelter, a novel webextension with a supporting library that addresses privacy loopholes and enhances security features in browsers, based on extensive research and real-world deployment.

Findings

Discovered a loophole in sensor timestamp APIs allowing device boot time observation.

Thousands of users worldwide use JShelter daily, demonstrating practical adoption.

Provides a fingerprinting report tool to aid future security research.

Abstract

The web is used daily by billions. Even so, users are not protected from many threats by default. This position 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 misused by previous research. 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 surrounding physical environment and location. 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 security research and data protection authorities. Thousands of users around the world use the webextension every day.