[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
---------------------------------------+-----------------------------------
 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:
---------------------------------------+-----------------------------------

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>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online


More information about the tor-bugs mailing list