Nicholas Weaver is a staff researcher at the International Computer Science Institute in Berkeley, California.

Ars recently reviewed two "Tor routers," devices that are supposed to improve your privacy by routing all traffic through the Tor anonymity network. Although the initial release of Anonabox proved woefully insecure , the basic premise itself is flawed. Using these instead of the Tor Browser Bundle is bad: less secure and less private than simply not using these "Tor Routers" in the first place. They are, in a word, EPICFAIL.

There are four possible spies on your traffic when you use these Tor "routers," those who can both see what you do and potentially attack your communication: your ISP, the websites themselves, the Tor exit routers, and the NSA with its 5EYES buddies.

It's true that these devices do protect you against your ISP. And if your ISP wants to extort over $30 per month for them to not spy on you, this does offer protection. But if you want protection from your ISP, just use a VPN service or run your own VPN using Amazon EC2 ($9.50/month plus $.09/GB bandwidth for a t2 micro instance). These services offer much better performance and equal privacy. At the same time, if your ISP wants to extort your privacy, choose a different ISP.

The second spy is websites and the nest of privacy trackers, advertisement trackers, permacookies, browser fingerprints, and other elements that make up the modern Web. Websites know who you are, and if you happen to also visit from elsewhere, they can know where you've been. If you visit the same site from a Starbucks, your non-Tor behavior can be tracked and linked to your Tor behavior.

The third is the Tor network. Tor is run by volunteers, and anyone (willing to put up with a bit of grief) can run an "exit node," a system which routes traffic from Tor onto the general Internet.

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Not only is this a public service, but running an exit node offers the opportunity to play spy, observing or even modifying all unencrypted traffic coming through the relay . And it's not just security researchers: malicious Tor exit nodes have even actively modified downloaded binaries! It's obvious, but normal Web surfers are not affected by malicious Tor nodes, only Tor users.

Last but hardly least, there are the spooks. EPICFAIL isn't just some joke; it's the name of an actual NSA program explicitly designed to deanonymize and track Tor users. For a large number of tracking cookies, the NSA's wiretaps record where they are seen, link them to other tracking cookies and, where possible, identify the users, shipping the results back to a central database accessible through MARINA.

EPICFAIL simply takes advantage of the NSA's existing pool of information. When the NSA's database records a tracking cookie from both a Tor exit node and a non-Tor IP, it notes this fact. There are several data structures (such as Bloom filters) which make the check easy to perform when ingesting this data. Now to deanonymize a Tor user, the analyst just looks up the associated tracking cookies through EPICFAIL, finds their identities, and goes from there.

So not only does using these Tor routers not hide you from the NSA, they specifically mark your behavior as "interesting" and worthy of further examination!

This problem is amplified by the woeful privacy protections present in modern Web browsers. There are cookies, flash cookies, HTML5 local storage, HSTS pinning sets, and passive fingerprinting. Although private browsing modes and anti-tracking extensions help, they require constant usage, continuously relogging into sites, and they don't cover everything.

The only way to be sure your Web browser isn't fingerprintable is to run a hardened browser designed to resist tracking, something that retains no history, doesn't enable Flash or other plug-ins, limits the opportunity for passive fingerprinting, and attempts to always use encrypted connections.

There is one such Web browser: Tor Browser Bundle, either standalone or running under Tails. Using anything other than TorBB with Tor really is EPICFAIL, reducing your privacy and security while marking your traffic as explicitly interesting. It's not just Tor that frustrates the NSA, but the combination of Tor and TorBB's privacy-centric policies.

So why these "Tor Routers?" As near as I can tell, the only problem these devices solve is "how to separate Kickstarters from their money."