Re: expat hash collision fix too predictable?

[Sebastian Pipping <sebastian () pipping org>]

On 04.06.2016 16:54, cve-assign () mitre org wrote:
> > Please confirm that using CVE-2012-6702 for consequences of
> > "unanticipated internal calls to srand" is what you intended.
>
> Yes, we confirm that. (They are unanticipated both because of
> thread-safety concerns, and because it's possible for an application
> to have an important dependency on srand being called exactly once.)
>
>
> > The hash DoS vulnerability CVE-2012-0876 was fixed to some extend in
> > Expat 2.1.0, commit e3e81a6d
> > ...
> > The next release of Expat will not do internal calls to srand (or rand)
> > any more but extract and use entropy from other sources.
> > ...
> > I suppose hash initialization with (too little /) second-based
> > entropy still is part of the original CVE-2012-0876 (or the same again).
>
> Use CVE-2016-5300 for the separate issue in which the original choices
> of entropy source and RNG did not properly address the possibility of
> a successful hash DoS attack. In other words, the code changes (in the
> next release) to fix CVE-2016-5300 are needed because the original fix
> for CVE-2012-0876 was insufficient. (We use separate CVE IDs when
> follow-on work is needed to complete the solution to the same original
> vulnerability finding.)

Excellent, thank you!

https://sourceforge.net/p/expat/code_git/ci/07cc2fcacf81b32b2e06aa918df51756525240c0/

Best



Sebastian