Groups > comp.lang.python > #19035

Re: Hash stability

Date	2012-01-16 10:15 +0100
From	Heiko Wundram <modelnine@modelnine.org>
Subject	Re: Hash stability
References	(4 earlier) <4F12BC8A.9040205@modelnine.org> <jeugdp$e1b$1@dough.gmane.org> <4F12F9D8.5080904@modelnine.org> <jf0mgu$8ue$1@dough.gmane.org> <jf0o0l$gua$1@dough.gmane.org>
Newsgroups	comp.lang.python
Message-ID	<mailman.4789.1326705327.27778.python-list@python.org> (permalink)

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Am 16.01.2012 09:44, schrieb Christian Heimes:
> Am 16.01.2012 09:18, schrieb Peter Otten:
>> I've taken a quick look into the suds source; the good news is that you have
>> to change a single method, reader.Reader.mangle(), to fix the problem with
>> hash stability.
>>
>> However, I didn't see any code to deal with hash collisions at all.
>
> It smells like suds is vulnerable to cache poisoning.

That it is, yes, at least partially. Generally, this is only relevant in 
case you are actually caching DTDs (which is the default) and in case 
you are querying untrusted SOAP-servers (in which case you'll most 
likely/should not use caching anyway), and in case the attacker has 
control over the URL namespace of a DTD-serving host (because the 
host-part of the DTD URL is used in the cache filename, unhashed, only 
the actual path is hashed to form the cache index).

The easier way to poison the cache is most probably through actual 
traffic modification, as most DTD URLs are served through plain http and 
thus are suspect to MitM-modifications, anyway.

-- 
--- Heiko.

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Hash stability Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-14 04:42 +0000
  Re: Hash stability Peter Otten <__peter__@web.de> - 2012-01-14 10:46 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-14 23:45 +0100
  Re: Hash stability Chris Angelico <rosuav@gmail.com> - 2012-01-15 11:36 +1100
    Re: Hash stability Bryan <bryanjugglercryptographer@yahoo.com> - 2012-01-15 04:03 -0800
      Re: Hash stability Chris Angelico <rosuav@gmail.com> - 2012-01-15 23:21 +1100
  Re: Hash stability Roy Smith <roy@panix.com> - 2012-01-14 21:26 -0500
    Re: Hash stability Terry Reedy <tjreedy@udel.edu> - 2012-01-14 23:07 -0500
  Re: Hash stability Stefan Behnel <stefan_ml@behnel.de> - 2012-01-15 11:13 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-15 12:46 +0100
  Re: Hash stability Peter Otten <__peter__@web.de> - 2012-01-15 13:22 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-15 17:07 +0100
  Re: Hash stability Chris Angelico <rosuav@gmail.com> - 2012-01-16 03:13 +1100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-15 17:51 +0100
  Re: Hash stability Stefan Behnel <stefan_ml@behnel.de> - 2012-01-15 18:20 +0100
  Re: Hash stability Peter Otten <__peter__@web.de> - 2012-01-16 09:18 +0100
  Re: Hash stability Christian Heimes <lists@cheimes.de> - 2012-01-16 09:44 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-16 10:15 +0100

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