[Facebooker-talk] Possible Security Hole in Facebooker -- Please Update!

[vincent chu]

Hi David ---

I took a look at your fix. Though I'm somewhat unfamiliar with exactly what
you want to do, I think it would be prudent to validate that the incoming
params hash actually originates from facebook before using the parameters to
reset the adapter. This way, you never touch the adapter until you're sure
that it's Facebook sending the request, and not some malicious actor.

Cheers,

Vince
----
Vincent Chu
Department of Applied Physics
Geballe Laboratory of Advanced Materials
McCullough Bldg. 318
476 Lomita Mall
Stanford, CA, 94305


Consider this:
"The smallest positive integer not definable in under eleven words."


On Wed, Feb 25, 2009 at 9:02 AM, kevin lochner <klochner at gmail.com> wrote:

> I was short on time and unfamiliar with the code when I put the fix in,
> which is why I went with the nuclear option of removing the before filter.
> I was a little surprised to see all tests passing with the before filter
> removed.
> In addition to user-verification of the fix, we could use a test breaking
> the old version and working under david's new patch.  Unfortunately I'm low
> on spare cycles . . .
>
>  - kevin
>
>
> On Feb 25, 2009, at 11:00 AM, David Clements wrote:
>
> In case it got lost in my grumpiness last night.
>
> The patch to fix this issue simply turned off adapter support.  Is that
> correct?
>
> I sent a pull request from my fork
> http://github.com/digidigo/facebooker/tree/master  which should fix the
> issue and preserve the behavior.  If anyone is using Facebooker to run
> multiple apps or Bebo it would be great if you could check it out and make
> sure that it didn't break.
>
> Thanks,
>
> Dave
>
> On 2/24/09, vincent chu <vincentchu at gmail.com> wrote:
>>
>> Hi all ---
>>
>> In the course of developing our Facebook connect app, we realized that
>> there was a  security hole in Facebooker that allows any malicious user to
>> change the state of the Facebooker module and crash any controller/view that
>> uses Facebooker to capture a Facebook session. For Facebook connect apps,
>> this could potentially be in any view that uses the "set_facebook_session"
>> before_filter.
>>
>> All the malicious user has to do is send a malformed HTTP request similar
>> to:
>>
>> http://my.rails.app.com/some_controller/?fb_sig_api_key=you_are_pwned
>>
>> The problem comes in the 'set_adapter' method of
>> 'facebooker/lib/facebooker/rails/controller.rb' where Facebooker will
>> attempt to load an adapter from the params hash if fb_sig_api_key is in the
>> request (ignoring the configuration found in the facebooker.yml file). In
>> this case, Facebooker would dutifully set the api_key to "you_are_pwned" and
>> any subsequent call to Facebooker would try and use "you_are_pwned" as the
>> api_key, causing it to crash the site.
>>
>> Kevin Lochner's already pushed an update to github, so update to the
>> latest commit:
>>
>> 6a954874369354324d87b2fe09c24db4bd485faf
>>
>> http://github.com/mmangino/facebooker/commit/6a954874369354324d87b2fe09c24db4bd485faf
>>
>> Cheers,
>>
>> Vince
>>
>> ----
>> Vincent Chu
>> Department of Applied Physics
>> Geballe Laboratory of Advanced Materials
>> McCullough Bldg. 318
>> 476 Lomita Mall
>> Stanford, CA, 94305
>>
>> Consider this:
>> "The smallest positive integer not definable in under eleven words."
>>
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>> http://rubyforge.org/mailman/listinfo/facebooker-talk
>>
>>
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