I am planning on using IdentityServer4 exclusively as an OIDC proxy to implement a single sign-on scenario relying on an external login provider (ADFS3 for starters, but there might be others in the future). Put it another way, no local users will ever exist, and neither do I expect to have any login or consent screens.
I've been reading the docs and studying the quickstarts source code, and even though I believe now I have more or less complete picture of how external login works, there's this one thing that I am still not sure about.
Namely, would it be safe and reasonable to do the following:
Do not implement any user store (neither ASP .NET Identity nor even an in-memory one);
Ignore the EnableLocalLogin client setting and always assume it's set to true;
Always force ExternalLogin from the login page?
A side question: are there any pitfalls if the primary client would be a JavaScript SPA? I do know this type of client is generally supported by IdentityServer, but it's the chain of redirects involved in the external login scenario makes me a bit worried.
Related
We have built a React web application that authenticates users with Microsoft via OAuth ( #azure/msal-browser package). Users are redirected to Microsoft auth page during signin, and then redirected back to our site once authentication has completed successfully. This is all working as expected.
However, we are in a position where we wish to add a custom PIN mechanism to protect some of our workflows. PINs will be encrypted/salted and stored in our own API, along with the existing mapping between Microsoft/Azure users and our own user state/records. In order for users to change/reset their PIN, we want to force them to reauthenticate with Microsoft before changing their PIN. I have not dealt with OAuth2 in a while, and am not entirely certain how this might be possible (since current auth workflow does not involve our server at all).
Ideally, users would navigate to the "Reset PIN" page and initiate the workflow. If possible, authentication would be handled through a pop-up (so as to not lose page state), which I think is possible as per documentation? If this is not possible, even a redirect to the same page with a specific query parameter (to indicate post-authentication) could work. The user would then be able to change/confirm their new PIN. At this point, a request would be sent to our API, including both the PIN and something from Microsoft that would allow our server to validate that the user did indeed just re-authenticate (proving they can change the PIN).
The primary sticking point is that our API must be able to verify that the user has just re-authenticated with Microsoft! One way to think about it would be that if a user gained temporary access to an unlocked authenticated workstation, they should not be able to perform restricted actions (as they do not know the PIN), nor be able to change the PIN (as they do not know the user's credentials). Yes, yes, I know physical access is effectively a compromise to any security, but this is a higher-level requirement...
I am guessing this workflow is possible, but am not certain how it might be possible. Would we use a different authentication workflow for this particular use case? Any pointers on a workflow we could investigate or use for this?
I can give you some info about how this should work. This type of flow can require a high level of extensibility in the authorization server though.
CLIENT REDIRECT
The client can send the OpenID Connect acr_values parameter, indicating the assurance levels it requires. In your case you would send two values.
CUSTOM AUTHENTICATION FACTOR
The user will perform standard authentication first, eg passwords. Then you would implement a custom second factor that uses the user identity and some custom logic to call your custom API.
ACCESS TOKENS
After authentication has completed, the authorization server will issue access tokens to the client. High privilege claims should only be included when strong authentication has been used. Some kind of scripting would be used here, that can read authentication result attributes.
API AUTHORIZATION
APIs should receive short lived access tokens. If it contains the high privilege claim, you know that your PIN requirements have been met.
CAN YOU SIMPLIFY?
It feels suspect to do your own PIN management. Can you outsource this, eg use a second factor of time based one time password (TOTP) instead? Mobile platforms such as the Google authenticator app provide tested solutions.
Is client side authentication "like on SPAs" just a lie to prevent users who choose to believe it from trying to play with the data on the back end "which protected with real authentication"?
Because when we develop spa with ['vue, vue-router', 'react, react-router'] we do a layer of authentication that operates on client and client side data (stores, and localstorage) and since we ship all the code to the end user is that make the authentication code is just a lie and easy to find a way to hack around it?
"yes the API is protected because the data on the API is there on the API"
I am not saying that should we develop spa without authentication and protected routes, but does it work with users who know some js and have the curiosity to access our app UI "at least the ui"?
In a sense, yes. When there is client-side logic that checks a user's role or authentication access, that is for the sake of usability rather than security and should be present only in addition to the actual secure checks on the backend.
For example, a well-structured SPA might choose to redirect a non-admin user away from a /admin page they are not supposed to access. This does not have anything to do with the actual security, it's just to avoid confusion and a seemingly-broken app when the actually-secure API endpoints called by that page inevitably return 403s.
Background
I am looking at the OAuth 2.0 Implicit Grant flow where a user is redirected to an authentication service and a JWT token is sent back a Single Page Application(SPA). The token is stored in a cookie or in local storage and, in the examples i have seen, the application will hide/show certain pages based on whether it can find the token in storage.
Issue
The problem is that in all the examples (official from service providers), i was able to manually add any random but properly formed token to the browser's local storage and got access to the 'secured' pages.
It was explained to me that you cannot validate the token in the SPA because that would require exposing the client secret and that you should validate the token on the API server. This means that you can 'hide' the pages but it is really easy to see them if someone wants to. Having said that you are unlikely to cause any real damage because any data retrieval or actions would need to go through the API server and the token should be validated there.
This is not really a vulnerability but the documentation and examples I have seen do not explicitly cover this nuance and i think that it could lead naive programmers (like myself) to think that some pages are completely secure when it is not strictly the case.
Question
It would be really appreciated if, someone who is better informed than i am, confirm that this is indeed how SPA authentication supposed to work?
I am far from an expert, but I have played a bit in this space. My impression is that you are correct, any showing/hiding of functionality based solely on the presence of a token is easily spoofed. Your SPA could, of course, get into verifying an access token.
But that may just make it a little more challenging to spoof. If someone wants to fake the client into thinking it has a valid token, they can likely manipulate the client-side JS to do that. Unfortunately that's the nature of client-side JS. Much of the code can be manipulated in the browser.
Thus far this is speaking to protecting the user from seeing a UI/UX. Most applications are only beneficial when they have data to populate their UI. That's where the API access token strategy is still sound. The server will verify the token and not give the client any data without it.
So while it's unfortunate that JS can be easily spoofed and manipulated to show things the developer would rather not make visible, this isn't typically a deal-breaker. If you have some awesome UI feature that doesn't need data, and you need to secure access to that UI itself, this model may not be the greatest.
I'm building an admin page for an application and have a state value 'authenticated' that flips from 'false' to 'true' after a successful login (which is authenticated on the server) which then shows the actual admin panel.
Are component state values safe from tampering by the client? Basically, if the client can modify my 'authenticated' state value to 'true', they can skip the login and go straight to the admin panel (which I obviously don't want).
I read that React Dev Tools allows the client to modify values yet everyone says "validate on the server" but I am validating on the server and updating my state accordingly, if the user is approved. If it is not wise to have a state value manage this, what is the right way to conditionally show the admin page after a successful, server-side authenticated login?
I think this is an important question since tampering with state values in a React app can have huge negative consequences on data integrity within an app/database.
TL;DR: Either require an authentication token with every request or require authentication through a session.
Never trust users always. One potentially big issue is if you "hide" admin actions behind the admins page without requiring authentication.
For example, assume the backend server uses a REST API to accept commands. In the admin panel you get links to administrative actions like a button 'Delete Everything' that sends a DELETE request to server.net:8080/api/admin/everything without requiring any authentication. If you're a user, you can find that in the code potentially and then send a DELETE request to that address from anywhere without any repercussions.
We'd never give administrative privileges to anyone who would want to delete everything... Because we'll never untrust someone. Right?
Worse, someone might find the server and fuzz some inputs to it, and oops! They manage to delete everything (or even worse, GET everything stored in the database). This wouldn't be hard to do, especially if the server you use to authenticate is the same server you use to issue commands. History has proven "security through obscurity" to be a very bad paradigm. Every action should be authenticated, even if it seems like the actions will be hard to find.
Generally, providing a JSON web token or some other form of authentication token and having the user send that with every request is a good start at least, especially if it has an expiration date. The token would be provided through a separate request with valid credentials.
Sending a token with every single request obviously isn't ideal. There are a couple of other things to try. For servers using PHP, you can probably trust sessions (though very many people who know more than me would probably disagree). In more modern cases, you could try to use Web Sockets, requiring the token after connection. Then only after authentication with the token do you allow the user to make administrative requests.
That way, even if a user knows the exact command they can send to perform any action, the server won't let them without a current session or token. Unfortunately, unless you're already using Web Sockets or depending on a session, it will likely require a lot of changes. I'd consider this to be critical though.
It is always possible to tamper values in the front-end, there is no way you can rely solely on the front end to ensure security.
Your best approach is to implement some form of authentication and authorization on your backend. In this way, even is some users pretend to be admin, they will be blocked when you do the next request to the server.
Perhaps if you can send more information regarding your problem, we can think of a more specific solution.
In a regular web app, when someone logs into the system they simply save an encrypted cookie that gets send on each request and the backend decrypts the cookie and uses the e.g. user_id/guid to lookup the user.
How do things differ when authenticating with a angular app?
Is there anything else to consider or it is basically the same process?
We use more or less the same mechanism.
Access to the application as a whole requires authentication - that is unless you're logged in, you don't get any of the javascript experience at all. This could make the login / login failure much less wizzy for the user, but in our authentication provider it's fine.
Part of our auth mechanism means the list of roles that the user has is a data object available within the browser. The javascript code uses this to decide which buttons / menus etc. are displayed. I checked with our security guy and he said something like "Well, it's a kind of direct object reference issue, but as long as each action is authorised properly, you're probably ok." So it's possible that a user could hack data values and change what they can see, but because of the next bit, they can't break our data (or see stuff that they shouldn't).
Each service call our javascript makes is authenticated and authorised. That is, the javascript call will fail if the auth token is missing or bad, but also, we internally match the auth token with a user and a set of permissions, and only execute that if the user is authorised to do so. (Note that this is good practice whether you're using Angular or not). Also note that this applies to GETs as well as POSTs - we don't want to give them data they should not see.
It gets much trickier if your API is hosted separately from your Angular site.