Full Disclosure mailing list archives
Re: tor vulnerabilities?
From: Alex <fd () daloo de>
Date: Thu, 04 Jul 2013 22:22:19 +0200
I run 5 tor nodes. I can tell that 5 nodes on the network are save for me. Trust tor. I will not run dsniff or tcpdump. Its save. I will never abuse the logins you gave me for free. Afk now, that one guy is surfing on xhamster, nice video choice
Am 3. Juli 2013 16:34:52 schrieb Georgi Guninski <guninski () guninski com>:
Valdis, I see no reason to trust tor. How do you disprove that at least (say) 42% of the tor network is malicious, trying to deanonymize everyone and logging everything? Or maybe some obscure feature deanonymize in O(1) :) On Sat, Jun 29, 2013 at 08:05:17PM -0400, Valdis.Kletnieks () vt edu wrote: > On Fri, 28 Jun 2013 23:37:45 -0400, Neel Rowhoiser said: > > I just stumbled across this and despite its sort of half-assed write up, I > > think its possibly an advisory? If I am understanding it correctly, they're> > saying that you can use a directory authority that hands out invalid/wrong RSA > > keys for other relays, you can cause decryption to fail and thus introduce path > > bias to nodes of the directory authorities choosing by selectively handing out> > valid RSA keys? > Oh, it's *that* attack again (as far as I can tell). Some French guys did a > proof-of-concept a few years ago that you could do this sort of thing if you > subverted a sufficient number of nodes. But keep reading. > > If the bit towards the end about guard nodes is correct, it would seem to> > indicate that they can use the semantics for detecting when a guard is causing > > too many extend relay cells to fail to cause valid guards to be marked invalid,> > and their rogue guards to succeed essentially using tor's semantics against> > them and causing the odds that you-re ingress point to the tor network is rogue> > to approach 1. > The problem is that you have to subvert a large number of relays to > do it, in a way that doesn't get noticed.. > > Why aren't the tor relay keys signed? And what other myriad of documents do > And who would sign said relay keys? They're all essentially self-signed > already, so what you're looking for is a PKI. And the whole point of the tor > system is that nobody involved trusts a central authority. If you've got a > good idea on how to do it, feel free to comment.> > directory authorities serve that also don't have integrity controls? This sort > > of makes me question the tor projects ability to deliver on any of the promises > > they make, as it would seem that a person needs like 3 or 4 rogue nodes before > > they could start de-anonymizing users, and the more of them they introduced the> > more of the network they could capture? > Actually, it's more like 3 or 4 *hundred* nodes. As I write this, there > are 3,903 relays connected, 1,218 guard nodes, and 2,396 directory mirrors. > http://torstatus.blutmagie.de/ > Even if you control 400 of those routers, the odds that any connection will > only traverse your nodes is only 0.1% or so. If you have "3 or 4', it's > literally a one-in-a-billion shot. Assuming a million tor tunnels form a > day, you'd catch one circuit every 3 years or so. And no guarantee that > the circuit you caught carried anything you would find useful.> I suppose you could bring up 4,000 tor nodes of your own, to increase your odds> of end-to-end control on a circuit all the way to 12% or so. However, that's > very much a one trick pony, and probably wouldn't work simply because people> would notice the sudden growth before you got enough nodes connected to do much> damage. > And using rogue directory servers to improve your odds doesn't help either. > Currently, there's a whole whopping 5 'bad exit' routers. You can improve > your chances by corrupting stuff so half the exits are bad - but again, that > will get noticed when a single-digit number hits three digits. And you need > to get it up to 4 digits before you have decent odds. > And yes, the Tor designers are totally aware that this "vulnerability" > exists - the problem is that all proposed solutions so far are even > worse (for instance, requiring signed relay keys). > > _______________________________________________ > Full-Disclosure - We believe in it. > Charter: http://lists.grok.org.uk/full-disclosure-charter.html > Hosted and sponsored by Secunia - http://secunia.com/ _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
_______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Current thread:
- Re: tor vulnerabilities? Georgi Guninski (Jul 03)
- Re: tor vulnerabilities? Valdis . Kletnieks (Jul 03)
- Re: tor vulnerabilities? adam (Jul 03)
- Re: tor vulnerabilities? coderman (Jul 03)
- Re: tor vulnerabilities? Georgi Guninski (Jul 04)
- Re: tor vulnerabilities? Michael T (Jul 04)
- Re: tor vulnerabilities? Valdis . Kletnieks (Jul 03)
- Re: tor vulnerabilities? Alex (Jul 04)
- Re: tor vulnerabilities? Valdis . Kletnieks (Jul 03)