Firebase is converting Email Provider accounts to other provider accounts - firebase

In my app, if a user registers using email and password, but later tries to log in or register using a Google account that shares that email, the account gets converted to a Google account and the user can no longer sign in with their email and password. I've configured the project with One account per email address setting on.
Is there any way of preventing this?

This is the expected behavior as Google accounts are verified: Firebase Overwrites Signin with Google Account
There are 2 ways around this:
1. Verify emails of password users. Google provider will be added to the account without unlinking the password if the user is verified.
2. You will need to switch to "multiple accounts per email", but this means 2 accounts will be created here, one email/password and another for Google.
I recommend the first approach. Firebase Auth does this for security reasons. Any person can claim an email. Unless the ownership is verified, the password must be unlinked to prevent the impersonator from gaining access to the account.

Related

Make sure a user verified their email before signing them in

I'm in the middle of adding firebase email/password sign in inside a React app. Specifically, it's an e-commerce site, and users will be signed in anonymously before they create an account (for things like cart data).
Here's the ideal user flow:
User registers by providing an email and password
User is not signed in immediately and instead gets a verification email
If a user tries signing in before verifying their email, they cannot sign in
User then clicks on the verification link and can sign in
I'm having issues with #3 because it appears like the only way to check if an email is verified is by calling:
const { user } = await firebase
.auth()
.signInWithEmailAndPassword(email, password)
if (user?.emailVerified) //let them enter the dashboard
However, this process signs in the user even if the email is not verified. That destroys the data on the anonymous account. And merging the two accounts isn't possible because the user thinks they are not signed in (hence it could cause UX issues if the accounts are already merged).
Any ideas?
If you're using the email+password provider, there is no way to prevent the user from signing in without a verified email address. You can of course keep them from using your app and accessing data, but you can't keep them from signing in.
If you want to ensure the user can only sign in after their email address has been verified, consider using the email link provider. You can then later allow them to set a password on the same account, either through the Admin SDK, or by creating a email+password account and linking that with the email link account. Also see the documentation on differentiating email/password from email link for some of the nuances here.

Can Firebase users created without a password still sign in?

In a scenario where a new Firebase user is created without a password, could the user sign in using just their email address (passing a null/empty string as the password)? Or does Firebase reject all attempts to authenticate with email + password when no password is specified in the user auth object?
The Firebase Admin SDK docs are clear that password is an optional property for createUser(), but the Password Authentication docs don't appear to specify Firebase's behavior when the user was created without a password. It would also be interesting whether an email link authentication (only) strategy can be enforced by leaving and/or setting a user's password as undefined, but this also doesn't appear to be explicitly called out in the docs.
Presumably Firebase rejects the email/password auth attempts, creating a de facto requirement for email link authentication (supported anecdotally), but any suggested links to Google authored docs would be greatly appreciated!
Firebase Authentication users are associated with one or more providers, and many of those providers don't need the user profile to have an associated password. For example: if you sign into Firebase with your Facebook account, the Firebase Authentication profile will not have an associated password. This applies to most providers, as in most cases the password is stored elsewhere (Facebook, Google, LinkedIn, Microsoft, etc), or ephemeral (email-link, phone auth).

Firebase recover password transforms account type

we are building an angular 5 app with Firebase.
We allow users to login with email+password or google account and we don't allow to have multiple accounts related to the same email address.
We built a form to allow users to ask for a Password Reset Email if they forgot their email password credentials and works perfectly if the user has an email+password account.
The problem arises when the reset email is asked for a google account. We'd expect for firebase to throw an error, not allowing to send the email, but the email is sent and if the user proceeds resetting the email the account is transformed from google type to an email+password.
Is there a way to prevent this behaviour ?
There is no way to prevent this. When a user resets their password, they are making a conscious decision to do so. Firebase is providing a way to recover an email account, in case it was hijacked. In the process all providers are unlinked and a password is set on the account.
You have a way to check if the email is associated with google provider or not. Checkout the fetchSignInMethodsForEmail and fetchProvidersForEmail APIs. These APIs would return the array of sign in methods or providers associated with an email.

Gmail auth has higher authority over Facebook auth - Firebase authentication [duplicate]

There doesn't seem to be any mention of this in the documentation, and all I found was this and this, where I would like to confirm this:
If there is an existing account with the same email address but
created with other credentials (e.g. password or non-trusted
provider), the previous credentials are removed for security reasons.
If a user signs in through Facebook or email/password and later through Google, their account sign in method is converted to Google. It only happens with Google and the setting for one account only is active.
Is it intended to be like this and is there any way to stop it?
As the documentation says: certain email domains have a trusted provider. Most prominently: Google is the trusted provider for #gmail.com addresses, since it's the only issuer of these email addresses.
If a user first registers their gmail address with say Facebook, and later there is a registration with that same gmail address from the Google provider, the latter registration is considered to overrule the former. If the user later signs in with Facebook again, the two accounts can be linked.
As far as I know, the only way to prevent this is to allow multiple accounts per email address.
Also see these posts by some of the Firebase Authentication engineers:
Firebase, login by same email different provider
https://github.com/firebase/FirebaseUI-Android/issues/1180
https://groups.google.com/d/msg/firebase-talk/ms_NVQem_Cw/8g7BFk1IAAAJ

Lose password after sign in using Google provider

I have an Android app with use Firebase authentication using email and password. Recently added Google provider now my users can sign in wih his Google account, the problem is the following
There's an existing user example#gmail.com registered on my app, later the user sign in with his Google account Firebase automatically change the provider of the account from email to Google, the problem the user sign out and try to login with his email/password and got a message
The password is invalid or the user does not have a password
I understand why happens, but users (you know they are users) get frustrated because can't login with his email/password
There's some way to tell Firebase to keep the user password or when a user login with Google and this convertion happens in order to notify to user
Note My app only allow one account per email
I found there's a method fetchProvidersForEmail I asume I can build a flow over that method that check which provider have the user and allow the user chose if want to keep if old password by asking and linking account or just continue

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