Silk Road forums
Discussion => Security => Topic started by: foxen624 on July 07, 2013, 04:49 pm
-
I have a couple of other layers of protection in place so I normally wouldn't be concerned either way. But my roommate has recently discovered TOR and doesn't seem to be very aware about such things as internet security.... uses the same computer for everything, doesn't know what a VPN is, etc.. and my only concern with this is because we share the same Internet connection and I'm not sure if the fact that we share an ISP could cause any security problems for me or anyone else who happens to be in the same relay... due to his lax attitude toward securing his own computer.
Also, the concept of switching identities prior to exiting the network is something that I have wondered about from time to time, but never really had a reason to dwell on it or spend much time trying to figure it out. However, now my idle curiosity is sort of turning into concern, so I tried to research it, on my own, but have not found much information pertaining directly to my question.
In trying to think it out, it would seem as if one has been on the SR for example, and maybe a couple other hidden services, that if after logging out of any hidden service(s) you've been to and just prior to stopping TOR and exiting the network, you switch identities. Would that not then put you on a totally different set of relays and make anywhere that you visited completely untraceable even if the exit node logged your IP? Wouldn't in the case of a malicious exit node attempting to track your activities, switching to a new identity make it appear as if you had been on TOR, went nowhere, then exited?
I'm sorry if this sounds stupid as I'm sure it is and it seems like something I'd normally not even have to think about. But for some reason, I can't seem to quite understand if what I suggested actually works the way I think it would.
Any input would be much appreciated... thanks :)
-
I don't think switching identities before closing TOR does anything to help you. There are millions of TOR users. Unless your a vendor in the boonies shipping out packages from your dinky post office in the middle of podunk nowhere then you can use TOR from your own internet connection without a problem.
-
I have a couple of other layers of protection in place so I normally wouldn't be concerned either way. But my roommate has recently discovered TOR and doesn't seem to be very aware about such things as internet security.... uses the same computer for everything, doesn't know what a VPN is, etc.. and my only concern with this is because we share the same Internet connection and I'm not sure if the fact that we share an ISP could cause any security problems for me or anyone else who happens to be in the same relay... due to his lax attitude toward securing his own computer.
Only if his internet activities cause the ISP to watch your connection or local LE to raid you. Otherwise, what he does on his computer has no effect on your computer, or your security, or your Tor circuits.
In trying to think it out, it would seem as if one has been on the SR for example, and maybe a couple other hidden services, that if after logging out of any hidden service(s) you've been to and just prior to stopping TOR and exiting the network, you switch identities. Would that not then put you on a totally different set of relays and make anywhere that you visited completely untraceable even if the exit node logged your IP? Wouldn't in the case of a malicious exit node attempting to track your activities, switching to a new identity make it appear as if you had been on TOR, went nowhere, then exited?
There is a theoretical attack where an adversary can determine which sites you are visiting by running a large number of relays, then looking for combinations of simultaneous destroy cells in the circuits passing through them. Your Tor client sends destroy cells when you shut it down. So let's say you build three circuits and are currently using one of them to visit web site A. You are unlucky enough to have picked the adversary's nodes once in each of your circuits. kmf has described it a few times on the forum. This is how it looks:
Circuit1 -> entry -> middle -> bad exit -> site A
Circuit2 -> entry -> bad middle -> exit
Circuit3 -> bad entry -> middle -> exit
You shut down your Tor client and send destroy cells to all the relays in those three circuits. The adversary notices that his relays (the "bad" ones above) get destroy cells at about the same time, so he concludes they came from the same client. Based on Circuit3, he knows who you are (your IP address). Circuit2 simply provides more confirmation in this case. Circuit1 tells him which site you are visiting, and that is how you get pwned, because he knows who you are and what you are doing.
If this attack could work at all, considering the large number of Tor clients and continuous circuit destruction that they see, it would mostly work on people visiting clearnet sites. The attacker would have to be both one of your entry guards and one of the hidden service's entry guards in order to identify which hidden service you are visiting, and that is much less likely to be the case than if he was one of entry and exit nodes.
The simple solution to this attack is to do exactly what you described: create a new identity, thus creating new circuits, before you shut down your Tor client. I think it is highly unlikely to happen and probably not worth doing, but that is a matter of academic debate.
-
Thank you all for your informative and considerate replies. Especially astor, your detailed description of the way the traffic travels on TOR in a worst case scenario has made clear to me now any lingering curiosity I had... thank you for that. And I did have so laugh at myself because I can't imagine that LE or even just a nosy person would find anything I do online interesting enough to go to any amount of trouble to pay any special attention to it. They would bore very quickly.
As I had written, my only concern was that I wasn't sure how sharing an internet connection with someone not terribly security conscious could have an effect on the security of my own computer... and you all have put that concern to rest.
Again, I thank you for having taken the time to address my question... what a great community this is :)