I agree it changes the boundaries.  I think this one needs moving.  As I said 
we hit a significant problem with this, which we solved by virtue of the fact 
that the target we were working with has an un-crumbed logout, so we could XSRF 
the logout.
 
It's something people get wrong and we should make a way to get it right.


________________________________

        From: Eran Hammer-Lahav [mailto:e...@hueniverse.com] 
        Sent: Tuesday, July 13, 2010 10:08 AM
        To: William Mills
        Cc: David Recordon; Colin Snover; OAuth WG
        Subject: Re: [OAUTH-WG] ' force_auth' request parameter
        
        
        The question is if we have consensus to force providers to support it. 
        
        
        It seems to overstep the boundaries we set over the years and it makes 
assumptions about how services authenticate users and obtain approvals. 

        EHL
        


        On Jul 13, 2010, at 13:05, William Mills <wmi...@yahoo-inc.com> wrote:
        
        

                I think it's a mistake not to have force_auth in the core.


________________________________

                        From: David Recordon [mailto:record...@gmail.com] 
                        Sent: Tuesday, July 13, 2010 9:58 AM
                        To: William Mills
                        Cc: Colin Snover; Eran Hammer-Lahav; OAuth WG
                        Subject: Re: [OAUTH-WG] ' force_auth' request parameter
                        
                        
                        I support immediate and a form of forced auth (ala 
OpenID's PAPE) but not in the core spec. They both should be part of an 
identity extension. 


                        On Tue, Jul 13, 2010 at 9:51 AM, William Mills < 
<mailto:wmi...@yahoo-inc.com> wmi...@yahoo-inc.com> wrote:
                        

                                I agree with Colin that some form of force_auth 
is needed.  I haven't read enough on the "immediate" proposal, but I know that 
we have run into the problem of trusting currently set cookies in the browser 
(even when we're actually sending a username/password and really do want to 
have an authentication).
                                 
                                I'm a +1 on the force_auth proposal.


________________________________

                                        From: <mailto:oauth-boun...@ietf.org> 
oauth-boun...@ietf.org [mailto: <mailto:oauth-boun...@ietf.org> 
oauth-boun...@ietf.org] On Behalf Of Colin Snover
                                        Sent: Tuesday, July 13, 2010 9:23 AM
                                        To: Eran Hammer-Lahav
                                        Cc: OAuth WG
                                        Subject: Re: [OAUTH-WG] ' force_auth' 
request parameter
                                        
                                        
                                        On 22/07/28164 13:59, Eran Hammer-Lahav 
wrote: 

                                        The following was submitted via the 
shared-copy page but does not belong with editorial feedback. This needs to be 
discussed and supported on the list before added the specification. I think it 
belongs where 'immediate' is specified.
                                        
                                        EHL
                                        
                                        ------ Forwarded Message
                                        

                                        From: An anonymous reader < 
<http://mail...@sharedcopy.com> mail...@sharedcopy.com>
                                        Date: Sat, 10 Jul 2010 11:01:11 -0700
                                        To: Eran Hammer-Lahav < 
<http://e...@hueniverse.com> e...@hueniverse.com>
                                        Subject: Re: draft-ietf-oauth-v2-09 - 
The OAuth 2.0 Protocol
                                        
                                        

                                        
                                        

                                         "Colin Snover" left these comments on 
your copy: 
                                         
                                        draft-ietf-oauth-v2-09 - The OAuth 2.0 
Protocol < <http://r6.sharedcopy.com/6bnqq8v> http://r6.sharedcopy.com/6bnqq8v> 
                                                
                                        
                                             As proposed on the ML, a new 
parameter to counteract the current behaviour of OAuth 1.0a authorization 
servers which is to assume that the account logged into the user-agent is the 
account that should be checked for access:
                                        
                                        force_auth
                                                 OPTIONAL. The parameter value 
must be set to "true" or "false".
                                        
                                                 If set to "true", the 
authorization server MUST prompt the end-user to authenticate and approve 
access. The authorization server MUST NOT make any assumptions as to the 
identity of the entity requesting access, even if another automatic mechanism 
is available to do so (e.g. browser cookies).
                                        
                                                 If set to "false" or not 
present, the authorization server MAY automatically grant access to the client 
if it is able to determine that access was previously granted.         link » < 
<http://r6.sharedcopy.com/6bnqq8v#shcp21> 
http://r6.sharedcopy.com/6bnqq8v#shcp21> 
                                         
                                        
                                        
<http://tools.ietf.org/html/draft-ietf-oauth-v2-09> 
tools.ietf.org/html/draft-ietf-oauth-v2-09 < <http://r6.sharedcopy.com/6bnqq8v> 
http://r6.sharedcopy.com/6bnqq8v>  · Original page < 
<http://tools.ietf.org/html/draft-ietf-oauth-v2-09> 
http://tools.ietf.org/html/draft-ietf-oauth-v2-09> 
                                          
                                         
                                        
________________________________

                                        via <http://sharedcopy.com> 
sharedcopy.com < <http://sharedcopy.com/?ef> http://sharedcopy.com/?ef>  
                                        

                                        
                                        ------ End of Forwarded Message
                                        


                                        Hi Eran,
                                        
                                        Sorry if that was not the right place 
for that to go; I didn't know what else to do. I have tried to solicit feedback 
from the ML regarding this parameter twice and nobody seems very keen in 
providing any, which is kind of a bummer. I waited until the last possible 
moment to add it in the hopes that someone would notice my messages and discuss 
it, but you made it sound like your plan was for draft 10 to be potentially 
final so I wanted to get it in before the deadline.
                                        
                                        I'm sure this is not a big deal for 
most applications that expect at most a single connection, but for me this is a 
huge deal since it completely immolates our application's authentication flow, 
and I can't go to every provider asking them to please change the way they 
implement the authentication portion of their OAuth API.
                                        
                                        In contrast to 'immediate', which had 
some concerns vis à vis security, force_auth is actually safer than the current 
normal flow used by most OAuth providers since it requires the provider to make 
no guesses about who is trying to authorize the app.
                                        
                                        Frankly, I think that OAuth providers 
do the wrong thing now in all cases by assuming that browser cookies are a safe 
way of confirming the identity of the end-user making an authorization request 
(they aren't!), but the spec says the way the authorization server 
authenticates the end-user is outside the scope of the spec. I have no 
objection to this-OAuth *should* be authentication-agnostic-but at the same 
time this is a very real and present implementation flaw and the only way to 
solve it is to make sure the spec defines a way for an application to say "hey, 
I know you *think* you know who should be authenticated, but *I* know that the 
user has requested to connect a *new* account, so don't use any automatic 
authentication method".
                                        
                                        I think it is incredibly important that 
the OAuth spec gets providers to distinguish between automatic & potentially 
unsafe authentication methods (like session cookies) versus more "guaranteed" 
authentication (like password), especially since 99.999% of the time OAuth 
relies on the end-user's Web browser which is all but guaranteed to contain 
some cookies for the provider that are unrelated to the requesting application.
                                        
                                        Examples:
                                        
                                        1. Multiple end-users with malicious 
intent. User 1 is logged into their Facetweetr account. User 2 wants to do bad 
things using User 1's account. Because the user-agent has cookies for user 1, 
user 2 gets to authorize their account with our app. Even when user 1 changes 
their password, unless the provider automatically invalidates their existing 
connections (the spec does not even mention doing this in an informative manner 
as far as I can tell), they are almost certainly unaware that the linked 
application is still able to perform actions on their behalf.
                                        
                                        2. Single end-user with multiple 
accounts. User is logged into Facetweetr account 1, but they want to authorize 
account 2. They go to authorize the application and are presented with a 
confirmation for account 1. They log out (because this is the only way to 
switch accounts on the provider) and suddenly the authorization flow is dropped 
on the floor. The user may not know immediately what they need to do at this 
point. They will need to manually return to the original application and 
restart the authorization request.
                                        
                                        3. User has two accounts that they want 
to authorize with a provider. User authorizes account 1 successfully, then 
wants to authorize account 2. Because account 1 is still logged in, and because 
the application already has a link to the account, it automatically redirects 
back to the application's redirection URI. In order for the user to get what 
they want, they are forced to manually navigate to the provider's site, log 
out, *then* begin the authorization request.
                                        
                                        These aren't imaginary scenarios; they 
are things that are going on *right now* with several different OAuth providers.
                                        
                                        The original request: < 
<http://www.mail-archive.com/oauth@ietf.org/msg02331.html> 
http://www.mail-archive.com/oauth@ietf.org/msg02331.html>
                                        
                                        Regards,
                                        
                                        -- 
                                        Colin Snover
                                        <http://zetafleet.com> 
http://zetafleet.com


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