The model for our product is like this:
Api backend (headless)
I already have oauth set up and ready to use with a resource owner credentials grant. Anyone who wants to use our api can do so using either an API key or their username/password. Of course they also need their client ID and secret.
SPA frontend that accesses the Api
I have built an SPA that will uses the api to provide a portal GUI for our clients. Given that this client-side app is owned and administrated by us (so it's a trusted app) how can I safely authenticate users using only username/password with oauth?
Originally it was using a JWT auth system that only required username/pass but now that we've implemented oauth I'd like to consolidate. It's unreasonable to make every user need to also have their client id and secret on hand to login, but I want users to have full access to the api from the GUI.
I've looking at using CSRF tokens but how would that work with my app when nothing is generated server-side?
I'm not sure how to proceed.
EDIT: very similar to the problem here.
I have decided to use the solution described here.
And here is a snippet of my implementation
The TL;DR version is
Create a proxy between the app and the api
Store the client ID and secret in the proxy
App logs in using password grant type -- proxy intercepts login request and inserts client id and secret
On login response proxy returns access token as an encrypted cookie
Client stores cookie and sends with api requests (to proxy)
Proxy decrypts cookie and inserts access token into Authorization header before forwarding to api endpoint
For me this has several advantages over implementing something custom on the api itself:
No need for custom grant on oauth server
ID/secret is hidden from app securely and can still use password grant
oauth server can identify client (no need for separate client ids for each user)
You should not use the resource owner credential grant from a JavaScript application. The fact that you own and administer the application does not make it a trusted application.
A trusted client is an application that can keep a secret. SPAs or any JavaScript app cannot keep a secret.
You should use the implicit grant for non-trusted clients.
Related
In Oauth and Openidconnect, the appserver endpoint invocation starts the Oauth flow and the app server gets the token from the auth server and is able to pass the token to resource server to access resources (delegation) on behalf of the resource owner.
The token exchange happens between the app server and resource server, and the token never arrives at the end users browser.
I'm working on a web api (aka app server) that will be consumed by a mobile app. There is no other server involved. Presently the login endpoint returns a signed JWT token to the user if correct credentials are supplied (validate against the db). User places this token in the header of the subsequent request.
Assuming I don't want to have a user db and validate logins, and instead delegate the auth check to another service like azure b2c or firebase (that use the Oauth), then I assume the flow is like given below:
Api registered the firebase/azure b2c (let's call this the provier) clientid, secret.
User invokes login endpoint of my api
The api invokes the provider's Oauth flow.
User gets popup to authenticate with the provider.
Eventually the provider will send the token (containing the claim like username) to the api (aka app server)
Does the user get back any token? Otherwise, when the user makes subsequent endpoint calls, then how is the endpoint able to identify who is this user and whether he is already authenticated?
Although it is okay to send back the access token to the user , but from the security best practise 's point of view , it is better not to do it which I quote the reasons as follow from this:
Because of the issues outlined above, the best security recommendation
for an SPA is to avoid keeping tokens in the browser at all. This can
be achieved with the help of a lightweight back-end component, often
described as a Backend-For-Frontend.
The backend component can then be configured as a confidential OAuth
client and used to keep tokens away from the browser. It can either be
stateful and keep tokens in custom storage, or stateless and store the
tokens in encrypted HTTP-only, same-site cookies. Whichever variant is
chosen, the backend component creates a session for the SPA, using
HTTP-only, secure, same-site cookies, thus enabling a high level of
security. Such cookies cannot be read by scripts and are limited to
the domain of the SPA. When combined with strict Content Security
Policy headers, such architecture can provide a robust protection
against stealing tokens
Also from here ,they suggest for mobile app 's OAuth2 best practise , it should perform the OAuth flow inside a system browser component.
I'm using an external service called auth0 in order to get an access token and let my users use my api. Auth0 is using Oauth2 protocol.
In short The user adds a username and a password, I'm doing a call to auth0 by using a client_id (apps have an id) and client_secret and I get an jwt access token in return. Then from there I carry this access token to have access to my own api since I can check its validity.
I have been looking around about how secure it is to store client_id and client_secret on the client side (e.g. web (javascript)/mobile (native or hybrid with ionic)) and everybody was saying that it's not secure since everybody can reverse engineer the code and get the client_id and client_secret. Ok...I can take it...what Can I do with them if I don't have credentials in order to get the access token?
Given that I don't want to store the client_id and the client_secret, one solutions I have thought is to make a direct call to my api (Java) with the credentials and then my api make a call to auth0 and return the corresponding access token. In this way the client_id and client_secret is stored in the backend and somebody cannot get them easily. Is that safe?
However I have some endpoints, e.g. creating use account, sending sms for phone validation etc, that cannot have credentials. How do I protect the api in such case? If I can't store my own access token on the client side how could I get an access token and access my own api without credentials?
Thanks
One possible solution that OAuth spec suggests is that you could have three different servers for your application.
client-side
backend server and an additional authentication server.
The preferred way of doing this would be that the client would send the user credentials to the authentication server. The authentication server would be a back-end server which contains the client secret
The authentication server will authenticate the credentials and return back the token.
The client will then use the token obtained from the authentication server to access the resource API server.
If you wanna know more check out this video
https://www.youtube.com/watch?v=rCkDE2me_qk
In my opinion you are almost certainly using the wrong OAuth flow. I use Auth0 with Ionic as both a web app and a native Cordova app. I don't have the client secret in my client code at all.
If you follow the Auth0 quickstarts (https://auth0.com/docs/quickstarts), you should be choosing (Native/Mobile App) if you are deploying to app stores, and (Single-Page App) if you are deploying the web version of Ionic. From there you can pick Cordova (for native) or Angular (for SPA). These should give you instructions that implement OAuth flows which DO NOT require your client secret. My guess would be you are referencing a "Regular Web App" quickstart, which runs server-side and CAN safely hold the client secret. That's not the world you're coding in if you are using Ionic Hybrid/Native.
I would consider wrapping the call to Auth0 into your own server side implementation as safe. Your API takes user credentials and then calls Auth0 and this way your client_id/secret are secure on your server and the client can be reverse-engineered all the way without compromising your security.
Regarding the other APIs which cannot have credentials you are pretty much out of luck. Their very use case is to be used by an unauthenticated third party, so at least the account creation API cannot really be protected. However you can still use some nicely designed constraints to limit the attack surface. E.g. you can require an email address/phone number to register and you will not allow the same address/phone number twice. If you set up your process that you first need to confirm your email address before you can validate your phone number this will make the life of an attacker a lot harder. He would need a real working email address, and some automation to receive your confirmation mails before he could get to call your SMS service. You could also rate-limit the service per IP-address so an attacker cannot cause your SMS cost to skyrocket by issuing a lot of calls for SMS validation in a short period of time.
I am using identity server 4, I followed the tutorial, so I have an api, mvc client, console client, and js client.
I saw this blog too, which is probably close to what I need:
https://medium.com/all-technology-feeds/testing-your-asp-net-core-webapi-secured-with-identityserver4-in-postman-97eee976aa16
what I need is an api, where clients can access data, but first, they need authenticate.
we also have the console client, which is also close to what I need.
The only issue with this examples is that in both cases client knows the secret. But in our case multiple clients should use the same api, and if they all have the same secret, they can log in on behalf of each other, but I don't want to have different secrets.
So what I think I could do is to create an api which takes username and password, and returns the token. But I am not sure if this is the right way to do things? This feels like a resource owner flow, which is not supposed to be used for client facing APIs if I am correct. But in that case, how should I go it?
thanks
It seems that there is some confusion. Allow me to give a short summary. First the terminology:
A user is a human that is using a registered client to access resources.
A client is a piece of software that requests tokens from IdentityServer - either for authenticating a user (requesting an identity token) or for accessing a resource (requesting an access token). A client must be first registered with IdentityServer before it can request tokens.
Resources are something you want to protect with IdentityServer - either identity data of your users, or APIs.
Client credentials: The simplest grant type and is used for server to server communication - tokens are always requested on behalf of a client, not a user.
Now about authentication. The client requests tokens at the IdentityServer endpoint. When you use a client in combination with the client credentials flow, then you'll need a clientid + secret. Where secret is really secret and should be known to the client only. You can't use the same secret here. Seems logical when compared to users, they don't share the same password either.
This is close to the resource owner flow, however a client cannot login as a user. For that you'll need another flow, like the hybrid flow. In that case the client logs in on behalf of the user. The difference is the presence of the "sub" claim (the id of the user) in the token.
The client in this case is your app: console or mvc. The first only supports client credentials where the secret is mandatory, the second supports a hybrid flow, where secret may be omitted:
In certain situations, clients need to authenticate with
identityserver, e.g.
confidential applications (aka clients) requesting tokens at the token endpoint
APIs validating reference tokens at the introspection endpoint
The Api is your resource, that you want to protect. The Api never authenticates a user or client. This is done by IdentityServer. It only verifies the token (using the IdentityServer4.AccessTokenValidation package). For that it has its own secret that should only be known to the Api.
In order to grant the client access to the resource you'll need to add the scope to the client in the configuration of IdentityServer. The client is then allowed, not required, to request a token that grants access to the resource.
Again, the Api has nothing to do with authentication. It is also not bound to one client. Multiple clients can access the resource. All you have to do is add the scope to each client that should have access to the resource.
So there is really nothing against it that clients and resources know their secret. You don't have to change anything. All you have to do is choose the appropriate flow.
My client asked me to develop a web api and use SAML as authentication.
I came across with the image below from this site, that shows the authentication flow.
However I don't know how to use the token that is generated after the authentication.
Do I need to store it as any other session variable?
Do I have to renew the token after a certain time or it lasts during all the session?
Note: The authorization server / idP is maintained by other party.
Since you develop the web API yourself, there's no need to refresh the token.
You're API needs to be added as relying party to the IdP. After that you can redirect to the IdP and initiate authentication. The token you get back contains several attributes (also configurable on the IdP) like unique user-id (uid), e-mail, name, country, etc...
In most cases this token is signed using a public/private key. Your API server needs to verify the signature, the issuer (the IdP), the audience (your API) of the token and consume the attributes. When everything is OK, you'll need to provision a local user account, link the external uid and create a local authentication cookie (or generate a OAuth2 token if your API uses OAUth2 or OpenIdConnect) for the locally provisioned user account.
Since this is a complex process, depending on the language/framework you're using, you might want to look into existing implementations.
I'm working on a personal project composed of an API and 4 clients (web, android, iOS, windows phone).
I'm using django-rest-framework and oauth2 toolkit on the API side and I wonder which grant_type would be more suitable in my situation.
I read somewhere that the implicit grant_type is appropriate for working with mobile clients.
I'm currently using the resource owner password credentials system.
My current workflow is:
The user creates an account on the API registration page (http://mysite/api/register) then gets redirected on the web client.
The user have to authenticate himself on the API from the web client (the secret and client ID are store in the web client). If the authentication is successful the access_token and refresh_token are both stored in the user session.
Each time the user want to access a page I verify if he is authenticated by requesting the API using his access_token. If the request fails, I retry with the refresh_token. If it's fails again I redirect the user on the auth page.
The user can use the API on a mobile client with the same account without extra manipulations (the secret and client ID are store in a secure location ex. share preferences or keychain)
I like this workflow, it's simple and convenient for the user: he registers once and can use all the clients and I get a perfect separation between the logic (API) and the UI (client). But I'm worried about the security of this system. I don't want to expose my users to threats. Do you guys have any thoughts, recommendations, suggestions?
You help in this matters would be very appreciated.
Thanks in advance!