Tor Browser Adds Sandbox

The newest release of the Tor browser for Linux now include a sandbox, which is designed to make it more difficult for attackers to exploit vulnerabilities. The Tor Project also is working on a sandbox mechanism for the browser on OS X.

Most of the major browsers have added sandboxes in recent years in an effort to defeat some of the more common exploitation techniques that attackers use. Sandboxes are meant to limit the damage that an exploit attempt against a given vulnerability can cause. The Tor Project has been working on a sandbox for its browser, which is based on Mozilla Firefox, for some time.

“On Linux the Tor Browser sandbox is centered around Linux namespaces along with seccomp-bpf, and attempts to reduce the attack surface available to adversaries to prevent exploits from succeeding, and to limit the capabilities of an attacker in the event that they do manage to compromise either the tor client instance or the browser itself,” the Tor Project said in a post.

“This is done by creating lightweight namespace based containers in which the Tor Browser components are run, with various restrictions imposed by the operating system. For example, the container that the browser runs in does not have an IP address to leak, or a connection to the external network except via Tor.”

Much of the malicious activity that targets average users is centered around the browser. Drive-by downloads and many other attack techniques use vulnerabilities in browsers to get control of victims’ machines. Sandboxes can help prevent these exploits from giving attackers access to the underlying operating system and other apps on the targeted machine. Some of the sandboxing technology is now included in the Tor Browser for OS X, as well.

“We have also made some progress with sandboxing on macOS. Building on the work done in the past by IronFox and similar projects, we have created sandbox profiles for the Tor daemon and for Tor Browser itself. These profiles, along with some command line scripts that use Apple’s sandbox-exec command to start Tor and Tor Browser, are included in our Tor Browser 6.5a6 OS X packages,” the Tor post says.

Image: Moyan Brenn, CC By license