Bug 8584 - CVE-2011-3414 not fixed
Summary: CVE-2011-3414 not fixed
Status: NEW
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.Web ()
Version: master
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2012-11-24 13:01 UTC by Julian Taylor
Modified: 2012-11-24 13:17 UTC (History)
1 user (show)

Is this bug a regression?: ---
Last known good build:

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.

Please create a new report for Bug 8584 on GitHub or Developer Community if you have new information to add and do not yet see a matching new report.

If the latest results still closely match this report, you can use the original description:

  • Export the original title and description: GitHub Markdown or Developer Community HTML
  • Copy the title and description into the new report. Adjust them to be up-to-date if needed.
  • Add your new information.

In special cases on GitHub you might also want the comments: GitHub Markdown with public comments

Related Links:

Description Julian Taylor 2012-11-24 13:01:48 UTC
I think CVE-2011-3414 is not really fixed in mono, the "secure" hash still allows to trivially create infinite collisions.
You attempted to fix it in this commit:

the algorithm looks like DJB31A were collisions can be created from any string with bytes x and y by changing them to x - 1 and y + 31
(to get infinite number of collisions you need to adapt that for integer overflows)

this method is completely independent of the seed.

note that python made a similar mistake in their fix, see http://bugs.python.org/issue14621
a proposed solution is to use siphash
Comment 1 Julian Taylor 2012-11-24 13:17:28 UTC
the seed does determine when the overflow occurs, which you need to know it to create more collisions
but as with this algorithm the integers overflows after 6-15 iterations you can very likely just guess this from the response times of the server in very few tries.