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Re: [tor-bugs] #4773 [Tor Bridge]: Implement Extended OR port (part of proposal 180)
#4773: Implement Extended OR port (part of proposal 180)
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Reporter: asn | Owner:
Type: defect | Status: new
Priority: normal | Milestone: Tor: 0.2.4.x-final
Component: Tor Bridge | Version:
Keywords: | Parent: #4685
Points: | Actualpoints:
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Comment(by asn):
Let's talk a bit about our security threat model.
The current (180) Extended ORPort design allows a local "attacker" to
connect to the Extended ORPort, spoof an arbitrary external address (using
USERADDR), and send Tor data. Furthermore, if we do the "the Extended
ORPort provides an identifier to be used in another port for
metadata/configuration transfer between tor and the proxy" idea, a local
"attacker" will be able to connect to the Extended ORPort, get an
identifier, connect to the other port, and configure the transport proxy
(for example, tweak its rate-limiting setup).
Would it be worth it to add some sort of authentication, so that only
pluggable transport proxies can use the Extended ORPort? A silly way of
doing it would be to add a key in a TOR_PT_* environment variable, but I'm
not sure if that would be secure in a cross-platform fashion [0].
That would also kill external proxies from using the Extended ORPort.
Would a file that can only be read by the Tor user, containing a cookie,
be better?
Are these "attacks" within our threat model?
[0]:
a related not-so-enlightening blog post
https://patternbuffer.wordpress.com/2008/05/05/unix-environment-variable-
scopesecurity/
We also assume that if the local attacker has root, the game is lost.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4773#comment:5>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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