[tor-bugs] #31460 [Circumvention/Snowflake]: Can attackers disable proxies by using their ID?

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#31460: Can attackers disable proxies by using their ID?
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     Reporter:  phw                      |      Owner:  (none)
         Type:  defect                   |     Status:  new
     Priority:  Medium                   |  Milestone:
    Component:  Circumvention/Snowflake  |    Version:
     Severity:  Normal                   |   Keywords:
Actual Points:                           |  Parent ID:
       Points:                           |   Reviewer:
      Sponsor:                           |
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 We just had the following discussion on IRC.

 {{{
 serna> If there are two proxies with the same sessionID
 serna> When the broker does the proxyAnswers it does the idToSnowflake
 which proxy would it return?
 serna> Suppose I'm an attacker, I would go to the broker's /debug page,
 scrape all the IDs and start sending requests to /proxy with those IDs
 continuously
   phw> cohosh, dcf1: ^
   phw> that's an interesting point. i'm not familiar enough with the code
 to answer this question but i'll forward it to snowflake's maintainers
 serna> phw: I did a little PoC with two proxies sending the same id and
 the broker didnt care, but the dangerous part is when an offer is accepted
 by the proxy and it sends the answer
 [...]
   phw> serna: this would effectively be a DoS issue, right? it may allow
 you to disable a given proxy.
 serna> phw: yes I believe it would be. If it works like I think it could
 disable every proxy connected to the broker
 }}}

 Is this an issue in our broker implementation?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31460>
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