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Re: [widgets] WARP and redirects

From: Robin Berjon <robin.berjon@gmail.com>
Date: Mon, 20 Jun 2011 12:57:28 +0200
Cc: public-webapps <public-webapps@w3.org>, Hari Kumar G <harig@opera.com>
Message-Id: <89FBF5E6-FA94-4885-88D3-F9A5070A46FB@gmail.com>
To: Marcos Caceres <marcosscaceres@gmail.com>
On Jun 20, 2011, at 12:23 , Marcos Caceres wrote:
> On Mon, Jun 20, 2011 at 11:41 AM, Robin Berjon <robin.berjon@gmail.com> wrote:
>> On Jun 2, 2011, at 09:53 , Marcos Caceres wrote:
>>> Consider this scenario: the widget requests access to www.google.com.
>>> On a local level google redirects to .pl or co.in . With WARP, if we
>>> checked redirects the local google page would be blocked. It would be
>>> impossible for any developer to take care of all those country wide
>>> domains in the normal way (and it does not scale). So we would want to
>>> allow this. Also in widgets XHRs resulting in 301s are followed and
>>> the final content is returned (this wasn't how it worked but was fixed
>>> later).
>>> 
>>> For a future version of WARP to work effectively, the spec should give
>>> the option of allow for redirects (or should do this automatically):
>>> 
>>> <access origin="http://x.com" redirects="true"/>
>> 
>> That's a security hole begging to happen. A lot of perfectly legit sites have a built-in redirect service. People use that, notably, to be notified of when a user leaves their site through a link they clicked, so instead of linking to http://berjon.com/ they link to http://nyt.com/redirect?to=http://berjon.com/.
>> 
>> So with your suggested approach, all a malicious widget has to do is request access to a perfectly valid data source under whatever false pretence, and then use its redirector service to go to evil.com, or to hit stuff that should be hidden on your private network:
>> 
>>    // grab all of Marcos's print jobs
>>    http://perfectly-legit.com/redirect?to=http://localhost:631/jobs?which_jobs=all
> 
> How it is any different in a browser?

You have origin restrictions in place. If you XHR to perfectly-legit.com and it redirects to something protected inside your network, unless you've used CORS to open up the latter (in which case you're begging to get hurt) then you won't get anything.

-- 
Robin Berjon
  Robineko (http://robineko.com/)
  Twitter: @robinberjon
Received on Monday, 20 June 2011 10:58:09 GMT

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