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Date: Tue, 21 Jul 2015 13:19:51 -0500
From: Kyle Kelley <rgbkrk@...il.com>
To: cve-assign@...re.org
Cc: oss-security@...ts.openwall.com, Muhammad A Khan <khanam@...ibm.com>, 
	security <security@...thon.org>
Subject: Re: CVE request: IPython CSRF validation

We realized that introducing CSRF everywhere in old releases was not going
to be backwards compatible, so we made more stringent decisions about
explicit Host and Origin checking. By design we don't protect against
untrusted clients, just cross-origin from regular browsers.

-- Kyle Kelley

On Tue, Jul 21, 2015 at 6:50 AM, <cve-assign@...re.org> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> > Software name: IPython notebook
> > Attack outcome: Possible remote execution
> > Patches:
> >   2.x:
> >
> https://github.com/ipython/ipython/commit/a05fe052a18810e92d9be8c1185952c13fe4e5b0
> >   3.x:
> >
> https://github.com/ipython/ipython/commit/1415a9710407e7c14900531813c15ba6165f0816
> >
> > POST requests exposed via the IPython REST API are vulnerable to
> > cross-site request forgery (CSRF). Web pages on different domains can
> make
> > non-AJAX POST requests to known IPython URLs, and IPython will honor
> them.
> > The user's browser will automatically send IPython cookies along with the
> > requests.
>
> Use CVE-2015-5607.
>
> This part of the patch seems unusual, but we haven't researched it at all:
>
>   host = self.request.headers.get("Host")
>   origin = self.request.headers.get("Origin")
>
>   # If no header is provided, assume it comes from a script/curl.
>   # We are only concerned with cross-site browser stuff here.
>   if origin is None or host is None:
>      return True
>
> Is this a case where it is safe to skip CSRF protection in all
> situations where the client omits an Origin header?
>
> - --
> CVE assignment team, MITRE CVE Numbering Authority
> M/S M300
> 202 Burlington Road, Bedford, MA 01730 USA
> [ PGP key available through http://cve.mitre.org/cve/request_id.html ]
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>



-- 
Kyle Kelley (@...krk <https://twitter.com/rgbkrk>; lambdaops.com,
developer.rackspace.com)

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