Researcher finds nearly 200 Chrome, Firefox, and Opera extensions vulnerable to attacks from malicious sites.
Malicious websites can exploit browser extension APIs to execute code inside the browser and steal sensitive information such as bookmarks, browsing history, and even user cookies.
The latter, an attacker can use to hijack a user's active login sessions and access sensitive accounts, such as email inboxes, social media profiles, or work-related accounts.
Furthermore, the same extension APIs can also be abused to trigger the download of malicious files and store them on the user device, and store and retrieve data in an extension's permanent storage, data that can later be used to track users across the web.
These types of attacks are not theoretical but have been proven in an academic paper published this month by Dolière Francis Somé, a researcher with the Université Côte d'Azur and with INRIA, a French researcher institute.
Somé created a tool and tested over 78,000 Chrome, Firefox, and Opera extensions. Through his efforts, he was able to identify 197 extensions that exposed internal extension API communication interfaces to web applications, allowing malicious websites a direct avenue to the data stored inside a user's browser, data that under normal circumstances only the extension's own code could have reached (when the proper permissions were obtained).
More details about Somé's work are available in a research paper entitled "EmPoWeb: Empowering Web Applications with Browser Extensions," available for download in a PDF format from here or here.
It would be highly impractical to list all the vulnerable extensions in this article. Readers can find the list of vulnerable extensions in tables at the end of the above-linked research papers.