This was covered by Motherboard[1]. The Tor Project put out the following statement in response: "the Tor network is secure and has only rarely been compromised. The Software Engineering Institute ("SEI") of Carnegie Mellon University (CMU) compromised the network in early 2014 by operating relays and tampering with user traffic. That vulnerability, like all other vulnerabilities, was patched as soon as we learned about it. The Tor network remains the best way for users to protect their privacy and security when communicating online."
I think that Tor, like Bitcoin, will always be vulnerable if a particularly powerful entity is able to obtain a majority of nodes. (Or, in the case of Bitcoin, a majority of hashing power).
And the more troubling aspect is that the courts have accepted the government's arguments that no warrant is required to disclose IP addresses:
> ... Tor users clearly lack a reasonable expectation of privacy in their IP addresses while using the Tor network. In other words, they are taking a significant gamble on any real expectation of privacy under those circumstances.
If both of these statements are true (that the government could easily run a majority of Tor relays, and that the government does not need a subpoena), then any particular vulnerability being patched is irrelevant to the inherent insecurity of the network.
Though note that Tor is also vulnerable to someone who doesn't control a majority of nodes, but can monitor the traffic of a majority of nodes from upstream. This is probably easier to achieve for a global adversary than actual control of the nodes' computation.
This doesn't make it bad software; it's the best we have, and being able to monitor traffic across the entire Internet is a huge ask of an attacker.
Also, remember that the NSA has had that kind of capabilities for a while, yet what came out of the Snowden leaks was “Tor stinks” (read: “We don't know how to break it in any practical sense”).
yup. Though apparently they could deanonymize some folks, but couldn't target the users they wanted.
But I'd expect that to change, a low-latency network like tor that also doesn't create cover traffic just architecturally isn't equipped to deal with something approaching a global passive adversary. Though networks for even that can be built..
The takeaway was indeed that they could deanonymise individual users, but they couldn't target it and it required significant amounts of human effort (i.e. it did not scale).
AFAIK, Tor developers are willing to implement cover traffic; the main reason it hasn't happened so far is that there is no known way to do this that clearly helps against that kind of threat. Until we have this (either from academic research, the Tor Project's own efforts or something else), it would be at best a placebo.
of course; but that's not tor's threat model anyhow. Nevermind the scenario of being mostly taken over; it also obviously falls to traffic analysis by a global passive observer.
In other words, its not gonna protect you from the NSA, ever, nor was it meant to. It might have a fightning chance against the FBI though. Actually it was surprising how in Snowden's files, the NSA was having trouble reliably deanonymizing targeted tor users.
[1] http://motherboard.vice.com/en_au/read/carnegie-mellon-unive...