Developers at the Tor Project have started working on a sandboxed version of the Tor Browser, currently available as an early alpha version for Linux systems.
Sandboxing is a security mechanism employed to separate running processes. In computer security, sandboxing an application means separating its process from the OS, so vulnerabilities in that app can't be leveraged to extend access to the underlying operating system.
This is because the sandboxed application works with its own separate portion of disk and memory that isn't linked with the OS.
Lack of sandboxing exposed Tor Browser users
Most modern browsers use sandboxed environments to run code their receive from websites. Chrome, Firefox, and Edge all use sandboxes to separate themselves from the OS.
Despite being based on Firefox, the Tor Browser did not use this technique, meaning it was far less secure, even if it provided more features to protect user privacy.
In recent years, the FBI has developed and deployed Tor exploits in order to identify and catch crooks hiding their identity using Tor.
While the FBI's intentions appear to be good, the Tor Project knows that this type of exploits can be used for other actions besides catching pedophiles and drug dealers. An exploit that unmasks Tor users can be very easily used to identify political dissidents or journalists investigating cases of corrupt politicians.
As such, protecting the Tor Browser against exploits and vulnerabilities that can expose the identity of its users is crucial.
The easiest way to do this is to support a sandboxing feature that isolates the Tor Browser from other OS processes and limits its ability to interact and query low-level operating system APIs that can expose MAC addresses, IP addresses, computer name, and more.
Work on sandboxed Tor Browser started in September
The Tor Project started working on a sandboxed version of the Tor Browser in September 2016. Over the weekend, Tor developers have released the first version of this new & improved Tor Browser.
As you can imagine, this is a very rough version. One of the Tor developers working on the project describes the browser as a "Gtk+3 based UI for downloading/installing/updating Tor Browser, configuring [T]or, and launching the sandboxed browser. Think `tor-browser-launcher`, that happens to run Tor Browser in a bunch of containers."
Currently, this version is in an early alpha stage, and only available for Linux. There are also no binaries available, and users must compile it themselves from the source code, which they can grab from here.