Re: [OAUTH-WG] need advice on sign out after performing sign in via OAuth 10x

[George Fletcher <[e-mail]>]

There is no standardization of the logout flow in OAuth or OpenID (there 
is in OpenID Connect as John mentioned) so your option 3...

    3) The third option : displaying some informative text when the user
    sings out from the application informing him that he/she signed out
    from our application only, and not from Google/other identity provider,
    seems to be the best option.

is the best option right now.

The problem is that as the application you don't know if the user signed 
in with Google just to access your app, or if they already had gmail 
open. In the first case it would be nice to sign the user out of Google 
since they authenticated solely for the purpose of accessing your app. 
In the second case you DON'T want to sign them out as that will kill 
their gmail session which is probably not what the user (or your app) wants.

So, informing the user that they are still logged in at Google is a good 
choice. You might want to give the user the option to forgo the warning 
in the future once they understand what is happening.

Thanks,
George

On 1/2/13 4:25 PM, Adrian Servenschi wrote:
> Hi guys,
>
> I am working on implementing login/registration with common identity 
> providers into our application.
> I am using Scribe for java library which implements the *OAuth* protocol.
>
> I've encountered what I consider a small security issue that I don't 
> know how to solve.
> If I sign in into our application via let's say Google and then I sign 
> out, the Google session cookie remains active in the browser.
> I can open Gmail afterwards in my browser and my inbox is displayed 
> without the need of authentication.
>
> Imagine that a user signs in to our application in an internet cafe, 
> then signs out and leaves the facility.
> A different client comes at the same desk, opens Gmail and he/she sees 
> the inbox of the first person.
> This can be a security hazard which I don't know how to solve.
> I see only 3 options:
>
> 1) I can leave it like this --> hazardous
> 2) If I use Google API to sign out the user from the Google when 
> performing Sign out from our application then the user will be signed 
> out from every Google application he has opened in his browser.
> In addition I heard that the documentation for performing Sign Out via 
> various identity providers APIs is not quite clear. But this still 
> needs to be investigated.
>
> 3) The third option : displaying some informative text when the user 
> sings out from the application informing him that he/she signed out 
> from our application only, and not from Google/other identity provider,
> seems to be the best option.
>
> I will highly appreciate if you can advise me regarding this issue.
> Thank you very much in advance!
>
> Adrian Servenschi.
>
> P.S. This is what I found on Facebook Platform Policies page 
> http://developers.facebook.com/policy/ 
> <http://developers.facebook.com/policy/>
> Your website must offer an explicit "Log Out" option that also logs 
> the user out of Facebook.
>
> So indeed a form of 3) option will be the best choice?
> Looking forward to your advices and suggestions.
>
>
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