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Tor best practices

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Re: Tor best practices

#31

Post by SamReidHughes »

An element of bad advice in this is the recommendation that you leave your cell phone turned on at home during your activities.

If "the feds" considered the possibility that this pattern of Tor activity in various wifi networks around the area all correlate to one person, they could then correlate the set of Tor uses with cell phones that sit motionless during those activities. This will completely out you unless you leave the cell phone in the same location all the time or for extremely large portions of time (a (1 - O(1/n))-sized proportion of your time) where n is the number of Tor sessions you want to perform. That's a bit pessimistic -- you could improve things by scheduling your Tor activity at times you would never be moving your cell phone anyway, and at times other people would consistently never be moving theirs -- a certain hour of the day. For example, suppose you never move your cell phone between 5 and 6 AM -- that's just a pattern in your life, and a pattern in others' lives, and if you scheduled your activity in that hour, you'd leak information much more slowly. But eventually, as more and more active cell phone users have the occasion to use their phone in the wee hours, it'll leak.

You also need to treat your personal internet activity and also perhaps electricity consumption (depending on metering technology) the same way as cell phone activity in this regard. You can't be going out using Tor at 5-6 AM some days and then be home browsing YouTube at 5-6 AM a small-ish proportion of the other days -- they'll nab you with 99.9999999% certainty in no time.

Edit: And you can't even be tired, or energetic, or have any measurable change in social activity before or after the Tor session either, of course.

Re: Tor best practices

#32

Post by nilved »

SamReidHughes wrote: post #29
nilved wrote: post #26

Earlier quoted context omitted.

But if you use Tor for all of your day-to-day browsing, in strict contrast with the OP's recommendation, then there's not such a glaring correlation.

You've still got the spike in network activity, and if you're running a relay, you've still got the spike in outgoing activity minus incoming activity.

Yes, but the local and remote activity can't be connected. Were somebody to connect and disconnect from Tor in the time surrounding an attack, you could; but you couldn't say that a Tor user is a culprit of an attack that went over the Tor network because they were using the Internet at the time. Perhaps they're just using Facebook or HN as they do many times each day.

Re: Tor best practices

#33

Post by Karunamon »

sligi wrote: post #24
tux wrote: post #21

It looks like author of this article is doing some shady shit. Using TOR and moving so much in different locations O_o Seems like his very paranoid. I think he forgot about "Faraday cage".

The only real reason people use Tor at all is for shady shit. They'll deny it all they want and bullshit on about "freedom", but not even Stallman is this autistic. Come on.

Please take this crap back to 4chan /g/ where it belongs.

Re: Tor best practices

#34

Post by blahbl4hblahtoo »

dobbsbob wrote: post #7
mihok wrote: post #3

I don't think the article mentions it, but in addition to the tips in the article, stay away from wireless or bluetooth connections, remove the card(s) if possible... While it might seem tin foil hat, any over-the-air communication is fairly trackable (not saying wired isn't). And while your computer or device tries to connect to a network, The control packets sent out to channel 0 will even send a list of preferred…

FBI also once had a carrier OTA update somebody's internet usb stick to broadcast their location

That's one that I do think it's cool to be paranoid about. Cellular networks were designed with lawful intercept in mind. Combine that with the work published recently about baseband processors and it looks to me like staying off of 4G networks is a good idea if you are doing something security sensitive.

Re: Tor best practices

#35

Post by SamReidHughes »

nilved wrote: post #32
SamReidHughes wrote: post #29

Earlier quoted context omitted.

You've still got the spike in network activity, and if you're running a relay, you've still got the spike in outgoing activity minus incoming activity.

Yes, but the local and remote activity can't be connected. Were somebody to connect and disconnect from Tor in the time surrounding an attack, you could; but you couldn't say that a Tor user is a culprit of an attack that went over the Tor network because they were using the Internet at the time. Perhaps they're just using Facebook or HN as they do many times each day.

Um, yes it can be connected. You have a graph that looks like /\_/-\_ of bandwidth differential on one machine and you have the graph that looks like /\_/-\_ of bandwidth used on the targeted machine. Case closed. The occasional connection to Facebook isn't going to obfuscate that.

Re: Tor best practices

#36

Post by foodbarf »

blahbl4hblahtoo wrote: post #30
nilved wrote: post #25

Earlier quoted context omitted.

> The public takedowns related to tor have been more about firefox than windows. But I get that Linux fans like to think that this is their sole bailiwick. It's not exactly fanboyism that makes security-conscious people prefer Linux. In fact, anybody with even a basic understanding of infosec knows that Windows should be considered wide open: Microsoft has backdoors, they give the NSA backdoors, and their code isn't…

I love that "Microsoft has backdoors"...no one credible has said that they have proof of that. They give the US Government early access to vulnerability data...they give those updates to several governments and large corporations early as the result of agreements they have made with big customers. They also let these same entities audit the source code for windows. Look it up. If you have the money and its important…

Microsoft employee, pls leave.

Re: Tor best practices

#37

Post by jagermo »

foodbarf wrote: post #36
blahbl4hblahtoo wrote: post #30

Earlier quoted context omitted.

I love that "Microsoft has backdoors"...no one credible has said that they have proof of that. They give the US Government early access to vulnerability data...they give those updates to several governments and large corporations early as the result of agreements they have made with big customers. They also let these same entities audit the source code for windows. Look it up. If you have the money and its important…

Microsoft employee, pls leave.

ah, come on. If someone comes up with "Microsoft has backdoors", you can always counter with "the NSA developed SELinux". Still, how many articles, strike that, theories did you read, that SELinux might not be as SE as "they" say? Just because someone points out a flaw, he is not (necessarily) an employee who wants to discredit the argument.

Re: Tor best practices

#38

Post by belorn »

While reading advice like those in the article, they seem to always leave out the most central aspect of security - the threat model. Doing some guessing, the following threats are mitigated by the article:

• An attacker has access to zero-day vulnerabilities to the software running on your device¹.

• You are storing non-Tor files on your device that can be used to build a profile against you. That or you are running OSX².

• That Flash and Java are horrible messes of software, and will break your security³.

• That Online tracking of your anonymous activities can later be used to connect your real identity with an anonymous session of tor usage. Deanonymization is a big research area but with rather little known results in the real world. Search data, social network profiles and large written texts have all been subject of deanonymization research.

• That Correlation attacks are practical if an attacker knows the entry node traffic and the exit node traffic. This is also a hot research subject, and the threat model can be created by for example reading the linked research on the tor blog⁴.

• Mixing you real identity with anonymous identity can cause harm.

• If you rent time at virtual hardware, the real hardware owners can see everything you do.

• An attack, presented in a 2013 research paper⁵, to verify if a hidden service is using a guard node owned by the attacker. It then assumes that a hidden service will randomly pick at least one of of 23 tor nodes with a probability of 90% if run under a period of 8 months for the cost of 60 USD per node per month.

I could not guess a threat model for "Your workstation must be a laptop". As a last line of defense, my workstation hard drive is equally easy to destroy with a hammer as my laptop. The cell phone advice is also quite bad - see SamReidHughes comment.

1: http://security.stackexchange.com/questions/40072/could-some...

2: https://research.torproject.org/techreports/tbb-forensic-ana...

3: https://www.torproject.org/docs/faq.html.en#UseTorWithJava and https://www.torproject.org/docs/faq.html.en#TBBFlash

4: https://blog.torproject.org/category/tags/entry-guards

5: http://www.ieee-security.org/TC/SP2013/papers/4977a080.pdf

Re: Tor best practices

#39

Post by wcummings »

blahbl4hblahtoo wrote: post #17

"1. don't use windows"...I realize how unpopular it is to question the groupthink on this site but this strikes me as simplistic. The public takedowns related to tor have been more about firefox than windows. But I get that Linux fans like to think that this is their sole bailiwick. If you are using tor and you are using a web browser as your primary means of communication AND YOU REQUIRE SAFTEY you have already made…

>"1. don't use windows"...I realize how unpopular it is to question the groupthink on this site but this strikes me as simplistic. The public takedowns related to tor have been more about firefox than windows. But I get that Linux fans like to think that this is their sole bailiwick.

The OS provides a number of security mechanisms which make exploitation harder, Windows' reputation for security (or lack thereof) is somewhat well-deserved, ask anyone who has done exploit R&D.

Even if you have an FF 0day, you still need to be able to weaponize it, bypass ASLR/DEP/etc and this may be more or less difficult depending on the target OS

Re: Tor best practices

#40

Post by jsmcgd »

belorn wrote: post #38

While reading advice like those in the article, they seem to always leave out the most central aspect of security - the threat model. Doing some guessing, the following threats are mitigated by the article: • An attacker has access to zero-day vulnerabilities to the software running on your device¹. • You are storing non-Tor files on your device that can be used to build a profile against you. That or you are running…

At the very least it looks like it is now essential to manually secure your router from firmware backdoors:

http://cryptome.org/2013/12/Full-Disclosure.pdf

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