Re: [OAUTH-WG] redircet_uri matching algorithm

+1 

     On Thursday, May 21, 2015 12:29 PM, Mike Jones <Michael.Jones@microsoft.com> wrote:

 +1

I vehemently concur that that working group should stay completely clear of facilitating this insecure practice.

                -- Mike

-----Original Message-----
From: OAuth [mailto:oauth-bounces@ietf.org] On Behalf Of Antonio Sanso
Sent: Thursday, May 21, 2015 12:41 AM
To: John Bradley
Cc: oauth@ietf.org
Subject: Re: [OAUTH-WG] redircet_uri matching algorithm

On May 21, 2015, at 4:35 AM, John Bradley <ve7jtb@ve7jtb.com> wrote:

> I think the correct answer is that clients should always assume exact redirect_uri matching, and servers should always enforce it.  
> 
> Anything else is asking for trouble.

FWIW I completely agree with John here...

regards

antonio

> 
> If clients need to maintain some state the correct thing to do is use the state parameter, and not append extra path or query elements to there redirect_uri.
> 
> A significant number of security problems in the wild come from servers not enforcing this.
> 
> I may be taking an excessively hard line, but partial matching is not something we should be encouraging by making easier.
> 
> I did do a draft on a way to safely use state https://tools.ietf.org/id/draft-bradley-oauth-jwt-encoded-state-04.txt
> 
> John B.
> 
> 
>> On May 16, 2015, at 4:43 AM, Patrick Gansterer <paroga@paroga.com> wrote:
>> 
>> "OAuth 2.0 Dynamic Client Registration Protocol" [1] is nearly finished and provides the possibility to register additional "Client Metadata".
>> 
>> OAuth 2.0 does not define any matching algorithm for the redirect_uris. The latest information on that topic I could find is [1], which is 5 years old. Is there any more recent discussion about it?
>> 
>> I'd suggest to add an OPTIONAL "redirect_uris_matching_method" client metadata. Possible valid values could be:
>> * "exact": The "redirect_uri" provided in a redirect-based flow must match exactly one of of the provided strings in the "redirect_uris" array.
>> * "prefix": The "redirect_uri" must begin with one of the "redirect_uris". (e.g. "http://example.com/path/subpath" would be valid with ["http://example.com/path/", "http://example.com/otherpath/"])
>> * "regex": The provided "redirect_uris" are threatened as regular expressions, which the "redirect_uri" will be matched against. (e.g. "http://subdomain.example.com/path5/" would be valid with ["^http:\\/\\/[a-z]+\\.example\\.com\\/path\\d+\\/"]
>> 
>> If not defined the server can choose any supported method, so we do not break existing implementations. On the other side it allows an client to make sure that a server supports a specific matching algorithm required by the client. ATM a client has no possibility to know how a server handles the redirect_uris.
>> 
>> [1] http://tools.ietf.org/html/draft-ietf-oauth-dyn-reg-29
>> [2] http://www.ietf.org/mail-archive/web/oauth/current/msg02617.html
>> 
>> --
>> Patrick Gansterer
>> 
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