Similar utility system - WebExtensions API - is also used on newer versions of Firefox, Edge, Vivaldi and Brave. Researchers do not test these browsers but think they are also affected.
The WebExtensions API protects the browser from attackers getting information about the installed utility by accessing the settings as manifest.json file inside each utility. This file will prevent the website from checking the file inside the utility unless the manifest.json allows it.
The team said that they discovered 'timed side channel attack on setup authentication'. The browser uses Chromium WebExtensions API which takes longer to respond to requests from the website for files stored on the computer with a fake utility when compared to the real utility but the wrong path.
chrome-extension: // [fakeExtID] / [fakePath]
chrome-extension: // [realExtID] / [fakePath]
This allows researchers to deduce which utilities are installed on the browser by sending a series of double requests and recording the time the browser needs to respond. This works for Chrome, Opera, Yandex Browser and Comodo Dragon.
Firefox is also affected, the current browser has moved from the old XML-based add-on API to Chromium-friendly WebExtensions API.
The researchers did not test because it was still in development but said that the old API add-on could still be hacked. Firefox also has special errors when requesting files from fake utilities.
The second error detected is called URL Leakage and affects the utility on Safari. They use the manifest.json file to restrict access to utility files. Instead, it generates random URLs for each session that only users can access while using the browser.
Researchers have figured out how to guess these random URLs. Tests showed that they could find 40.5% of the URL of the utility during the tests.
'We have published all the findings and are discussing with developers of a number of browsers and utilities to find ways to fix them, in order to reduce these attacks on the current versions. and the future, 'the team said.
In a research report called Extension Breakdown: Security Analysis of Browsers Extension Resources Control Policies, they also detail how these errors are used for analysis for advertising purposes as well as for malicious applications.