Using this page: https://developers.google.com/identity/sign-in/web/sign-in
It's really easy to add a button to a page for a client side only login with Google.
On Clicking the button, the user is presented with a screen like this:
There are 2 ux_mode for this button: "popup" and "redirect":
https://developers.google.com/identity/sign-in/web/reference
My question is about ux_mode=popup specifically, where the originating page doesn't change, and all the login flow is handled in a separate popup window.
Imagine a good app is published. It seems like an attacker could clone the app, present it to a user. The user thinking it's good app would login and the attacker would have a way to grab a valid token from the user for good app.
Now I understand that in that mode (popup), the IDP (Google) will reject anything that doesn't come from an Origin that is not part of the explicit list of redirect URIs set in the configuration of the project.
But is that the only thing that prevents this? I have read again and again that one should not rely on CORS for the security. Also I'm not sure but it seems that it can be circumvented with a little bit of crafting.
Is there another aspect of the security of this login flow I am missing?
I do not know google implementation but from OAuth 2 point of view:
1/ "The user thinking it's good app" user should check the address bar and a green lock in his browser. It is considered as a users responsibility.
2/ you registered redirect uris which are checked when client is trying to get access token. So google will reject to generate and redirect users browser to malicious app with the token.
3/ browser will reject any communication between popup window and other webpages since they are not same origin. This is called same origin policy and is considered as important security feature of a browser.
In general: app location/uri/origin/domain (as you want) is what identifys your app and security is based on that.
Hope it helped.
I'm planning to switch an app from the old OAuth flow with the SFSafariViewController to the new flow with iOS 11's SFAuthenticationSession. Logging in isn't an issue, the transfer to the new API took me a few minutes to implement. However logging out has me baffled.
How?
I can't find any mentioning of wanting to offer the option of logging out anywhere in the docs. Using the old SFSafariViewController to invalidate the cookies? Nope, they're not shared anymore with SFAuthenticationSession. As soon as I restart the authentication session the user get's logged in automatically and there's no way out. So how to enable logging out? Or am I simply overlooking something completely obvious?
Update:
I found a "way that works" in a technical sense, but it's bonkers for the user: Open a new SFAuthenticationSession on the logout page that clears the cookie. But that means when logging out the alert view asks the user again whether he'd like to log in via the service. If yes is selected ("logging in"), the cookie clearing logout page is opened, the user has to manually dismiss the view, which can be caught by the completion handler and we know we can open the login view again.. displaying the login prompt to log out? I really don't like this solution.
Any ideas? Am I still overlooking a completely obvious solution?
Update 2: As no one has any clue about this issue so far, this is probably not an easy one. I have filed a suggestion with Apple via their report tool to either clarify how to handle this or build it into the API if not available. Will post if I get an answer.
Update 3: After pondering the issue a bit more we found another possible (although also unattractive) solution if you can influence the login page of the OAuth provider: make cookies very short lived. Then the login page can be opened without automatic log in. However this kills the whole purpose of sharing login sessions between apps.. and you need to be able to influence the login page.
Update 4: Since iOS 12 SFAuthenticationSession is deprecated and got replaced by ASWebAuthenticationSession. However ASWebAuthenticationSession does not change anything in regard to logging out. It's still not possible. Same issue as before.
With ASWebAuthenticationSession, setting .prefersEphemeralWebBrowserSession to true prior to calling .start() will force the user to enter credentials in the browser session. While not the same as logging out, this will allow a new user to login with different credentials when launching the next session.
Update November 2020: We used #react-native-community/cookies to clear cookies as a workaround. See the snipped below as an example.
import CookieManager from '#react-native-community/cookies';
CookieManager.clearAll().catch(e => alert("Error deleting cookies during logout"))
Previous answer from April 2020. This may be helpful for anybody struggling with this. I've spent few hours testing different options, going through apps and looking how they do it and reading forums/discussions.
I haven't find a way to programatically clear cookies and there is no documentation on Apple on this.
Using FB as an example. Logging out from Safari and deleting FB app doesn't help. Any app which is downloaded will not ask for login to FB if you logged in once before through ASWebAuthenticationSession or SFAuthenticationSession.
If users ask how to force login (even though it's not your problem as a developer) you can point them to: Settings -> Safari -> Advanced -> Website Data -> Remove All Website Data (or just the ones for the provider).
If your use case needs switching of users (like in my case where we use Azure AD and users share 1 phone) you have 2 options. A) Open ASWebAuthenticationSession with the logout endpoint (as mentioned, this is very weird UX). B) Open Safari as a separate app (not inside yours) and do login/logout there. Unfortunately, there is no way to redirect the user to your app after logout if the OAuth provider doesn't support redirect on logout.
It sucks because this prevents developers from creating nice experiences on iOS for use cases where a business needs to share device between multiple users and OAuth is used as identity provider.
One of the “best” solutions I have come across is to open a logout page in system Safari (not an SFSafariViewController). Because ASWebAuthenticationSession shares cookies reliably with Safari, the expired/deleted cookie then also affects the app.
See this GitHub page for more details.
It depends on which cookie stores your login info;
If it is a session cookie, then it is not shared with Safari as per https://developer.apple.com/documentation/authenticationservices/aswebauthenticationsession
So, simply clear your local session, and the cookies will be cleared on the next app launch.
If not, and the cookie persists, then like Martin said above, you should open Safari (not SFSafariViewController) with your logout URL, then redirect back to your app.
Please let me know if you need more info. I have tested extensively with all 3 ways of authentication (ASWebAuthenticationSession, Safari, and SFSafariViewController).
For iOS 13.0 need to add SceneDelegate.swift for UISceneConfiguration
Also need to update appdelegate for UIScene implementation
Add UISceneSession Lifecycle
It is working fine this way SFAuthenticationSession issue resolved.
In one of our apps, we've already started using ASWebAuthenticationSession.
Our use case for this goes beyond just retrieving access and refresh tokens upon login. What I mean by this is, the same session cookie is used when opening the web app (whilst logged-in to the iOS app) in order to save the user from re-authenticating themselves again and again. Eventually, time comes when the user finally decides to log out of their account and may thereafter attempt to re-login again using a different account. Since the user's session cookie may still be alive by then, any re-login attempt only flashes the authentication screen momentarily, logging them in automatically back to their first account without giving them a chance to enter the credentials of the second account.
To really force the user to enter their credentials every time we present the authentication screen, we have to add to our Auth0 query params the prompt=login pair.
Here's what the URL would look like:
https://example.auth0.com/authorize?
client_id=abcd1234
&redirect_uri= https://example.com/callback
&scope=openid profile
&response_type=id_token
&prompt=login
You can find more info about this on this Auth0 doc: https://auth0.com/docs/authenticate/login/max-age-reauthentication
i am working with the HelloFacebookSample from face book's sdk.
i have a few issues, but am trying to get through them.
The one i have right now is that after I login, then logout, then login again, i am automatically logged in without being asked for credentials. Is there any way to change this behavior?
And secondly (for now), is there any way i can bring up the FB login dialog within my app instead of it going to Safari? i don't want my users to have access to safari at all, so i need to keep control.
The original FB sdk (about 2 years old) handled the login directly from within the app, so I am thinking i am just missing something here?
Thanks,
Jerry
If you want full control over the login process then you can't use the SDK, you need to add and manage a web view yourself. Facebook tries to bother the user to reconfirm as little as possible, so it will provide a login with the least path of resistance (and user taps / interaction).
Depending on how the user is logged into Facebook you won't be able to force them to re-enter login details unless you implement the web view approach. If you're using the SDK then you would need to call closeAndClearTokenInformation on the active session and also delete any Facebook related cookies from the app (and that's probably as close as you can get).
I have a Google Apps Marketplace (v2) app I am working on setting up Oauth2 for.
I've got everything working, but for some reason when I do a redirect to the authentication page, after, after you select which Google account to use (if like you're me and are testing, you have to pick one of several Google accounts you're currently signed into), I get sent to another page which seems utterly pointless:
This is bizarre and annoying, because I am logging in as the domain administrator!
Does anyone know a way to skip this screen, or what I might be doing to be cursed with this terrible user experience?
I just confirmed that having access_type=offline will always display this page, even with approval_prompt=auto. You will always get back a refresh token as well.
The only way to hide it is to remove access_type=offline on future login requests (ask only on signup).
I believe this shows up only if app requests refresh token for offline access. Also this should only appear first time you access the app after installation.
In order to skip this you need to update app to not request refresh tokens.
The new MVC5 web application templates are pretty nice. All you need to do is uncomment UseGoogleAuthentication() and you can log in using your google account. This works fine.
My question is with regards to the login-logout-login cycle. For instance, If I want to test my application with a different google accounts this currently does not work out of the box.
When you log-out it only drops the application cookie but google happily assumes that you want to stay logged-in and when you press google login it will use the account you've previously chosen and skip the account selection process.
As I understand it OWINs AuthenticationManager.SignOut is supposed to revoke the external cookie as well as the application cookie but this does not seem to be happening. bug or feature?
I'm aware of the prompt parameter (see this question) to force the behaviour however I don't want to force the prompt every time someone hits the app, only when you log-off and back on again.
Any chance for a simple solution? Seems strange that this is not supported.