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Re: question on 4.1 explicit intents

From: Jean-Claude Dufourd <jean-claude.dufourd@telecom-paristech.fr>
Date: Mon, 16 Jul 2012 13:35:57 +0200
Message-ID: <5003FC9D.3030806@telecom-paristech.fr>
To: Greg Billock <gbillock@google.com>
CC: "public-web-intents@w3.org" <public-web-intents@w3.org>
On 18/6/12 21:18 , Greg Billock wrote:
> If you mean restrictions on which pages may invoke intents, I'd need 
> to hear more about the security threat model you're thinking about. I 
> don't see yet how it's a real threat to allow any page to invoke any 
> intent. 
JCD: Quoting one colleague:
"If you extend intents to be able to communicate with local, client-side 
services (such as a smart TV) then an explicit intent seems like a big 
vulnerability - any webpage can attempt to invoke all local intent 
services it knows have implementation vulnerabilities.  This is also 
true of web-based systems, of course, but at least web pages are usually 
designed with malicious users in mind.
We don't want Web Intents to turn into another ActiveX disaster, where 
everyone registers new intent services with a browser and all the 
vulnerable ones are exploited. "


> For non-explicit intents, the security policy is very open-ended -- 
> that is, the UA is free to dispatch the intent in a way that can be 
> very responsive to the preferences of the user (and that's the whole 
> idea, after all). One goal for explicit intents is that they can be 
> used for intra-app transitions. (That is, an app could be built of 
> different intent handlers, and the transitions in the app 
> corresponding to good integration points with other apps.) For that 
> use case, app developers need to have predictability in the way those 
> invocations get handled. If there's a good justification, interposing 
> a registration step there is needed, but I don't see that being needed 
> at this point. 
JCD: If the goal of explicit intents is in-app intents, then there 
should be a restriction on which intents can be called explicitly, such 
as intents registered by the same domain as the invoking page, in a 
CORS-like mechanism.
The problem with explicit intents is specifically with outside 
invocation of locally-registered events, or more generally cross-origin 
invocations.
Best regards
JC

-- 
JC Dufourd
Directeur d'Etudes/Professor
Groupe Multimedia/Multimedia Group
Traitement du Signal et Images/Signal and Image Processing
Telecom ParisTech, 37-39 rue Dareau, 75014 Paris, France
Tel: +33145817733 - Mob: +33677843843 - Fax: +33145817144
Received on Monday, 16 July 2012 11:36:29 GMT

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