On 10/3/20 6:38 AM, nusenu wrote:
Me and several tor relay operator friends have questions about Malicious Tor exit nodes. How do you define a node as malicious ?
In the particular case (at least the initial detection): Traffic manipulation at the exit relays.
How bad is the situation now ?
This group [1] is still rather active and at this point they run a 3 digit number of relays, but it is not the only malicious group that is active on the Tor network and might not even be the group I worry about the most.
[1] https://medium.com/@nusenu/how-malicious-tor-relays-are-exploiting-users-in-...
Is there any other risk than ssl striping ?
I think so, yes. The good thing about ssl-stripping attacks is, that it is easy to protect against and easy to detect (if you are aware). The catch is that most users are probably not aware. So when compared with all other types of attacks that malicious relays can perform, ssl-stripping is probably not the biggest worry.
After the long discussion on the tor relay mailing list, what will be implemented as a solution ?
As far as I can see, nothing will change/be implemented in the near future at the Torproject or Tor directory authority level.
for Roger's (long term) plan see: https://gitlab.torproject.org/tpo/metrics/relay-search/-/issues/40001 linked from https://blog.torproject.org/bad-exit-relays-may-june-2020
- is there / will there be things
implemented as a conclusion of the "call for support for proposal to limit large scale attacks" ?
Nothing came out of that thread.
- has it been possible to prepare / set
up precautions to avoid this king of situation
I don't think anything has been implemented to prevent or reduce the risk of this from reoccurring.
Unfortunately, our OODA loops[1] on all development and funding actions are devastatingly, catastrophically long. This is due in part to slow funding cycles, and in part due to an internal debate over Agile vs Waterfall methodology[2]. I am in the Agile camp. I believe that Agile will help us respond to things like this in hours, days, or at most weeks, rather than months and years. Agile is how I ran the Tor Browser development.
We just signed a funding proposal that covers "network health", which in theory covers network scanning to find and respond to problems like this. However, the funding is scoped to scalability and performance work. It will be a little bit of a stretch to cover this type of exit scanning too, but at least we will have Tor Project staff allocated to this kind of work now.
The proposal took 18 months of background planning from us, ~6 months of background research from me, and a couple months of proposal review, with one revision round. Because of these issues on both sides, it has literally been years since we identified this problem area, and got funding to act on it.
The good news is we start Monday.
1. https://en.wikipedia.org/wiki/OODA_loop
2. https://www.seguetech.com/waterfall-vs-agile-methodology/