[tor-bugs] #27921 [Core Tor/Tor]: apparent DOS / impairment-of-service against FallbackDirs using DIR requests, please evaluate for possible mitigation

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#27921: apparent DOS / impairment-of-service against FallbackDirs using DIR
requests, please evaluate for possible mitigation
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 Reporter:  starlight     |          Owner:  (none)
     Type:  enhancement   |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: unspecified
Component:  Core Tor/Tor  |        Version:  Tor: 0.3.4.1-alpha
 Severity:  Normal        |     Resolution:
 Keywords:  tor-dos       |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
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Comment (by teor):

 Replying to [comment:14 starlight]:
 > what version of the daemon pulls _uncompressed_ full descriptors over
 the OR port?

 Either a very old tor, or stem, or some other custom code.

 > in what scenario would a dozen rotating tor-daemons-bots request so many
 descriptors it burns 3+ mbytes/sec from multiple fallback directories?

 Some kind of internal failure or bug. There are few rate-limits in the tor
 client code, there should be more.

 > IMO this is intentional in the way the circuit-extend attack was
 intentional: cause trouble, harass the network

 Quite possibly. But tor has also had "fast zombie" bugs in the past, so we
 should consider that possibility as well.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27921#comment:15>
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