[tor-bugs] #17901 [Tor]: Tor would bind ControlPort to public ip address if it has no localhost interface
Tor Bug Tracker & Wiki
blackhole at torproject.org
Wed Feb 3 11:51:21 UTC 2016
#17901: Tor would bind ControlPort to public ip address if it has no localhost
interface
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Reporter: s7r | Owner: teor
Type: defect | Status: needs_information
Priority: High | Milestone: Tor:
Component: Tor | 0.2.8.x-final
Severity: Major | Version: Tor: 0.2.6.10
Keywords: 027-backport 026-backport | Resolution:
Parent ID: | Actual Points:
Sponsor: | Points:
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Comment (by teor):
bugzilla raised concerns about this ticket on #17949:
> In general, localhost is a TLD, and it must be resolved through DNS. In
one of related tickets stated that 127.0.0.1 can be seamlessly redirected
to public IP by the system. DNS can return "not found". So, there are
enough reasons to stop rely on localhost as a security solution.
> General practice is that services listen on 0 (0.0.0.0 and/or [::]).
Address filtering is a task of firewall. To handle all tasks by tor
instance is not a good practice.
This issue happens only on machines where binding to 127.0.0.1 doesn't
bind to a loopback interface. This is non-standard OS behaviour /
configuration. On standards-conformant OSs, binding to 127.0.0.1 reliably
ensures that the port is not accessible outside the local machine,
reducing the attack surface considerably. People who configure their OS
any other way are vulnerable unless they take additional precautions. Tor
can detect serious security issues like this, close the port, and warn the
user. So we will do that, because it's more secure by default.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17901#comment:24>
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