Consider the following (common) scenario. I will first try to specify how I understand a (nice) Web API should look like, using OAuth. Please do correct me if I got any of the flows wrong.
My API: the center of attention, all clients use this.
My Web App: Uses the API just like any other client would.
My Mobile App: Also uses the API, the same exact way as the web app. Users should be able to authenticate without opening a browser.
3rd party Web App: Also uses the API - however, the user/resource owner must grant permission for the app to do something. They do this by redirecting to my site (or opening a popup to it), logging the user in if necessary, and prompting the user for access.
3rd party Mobile App: Same requirements as the 3rd party web app.
The Question(s)
Should the API handle authentication and authorization?
How does the API know who (the resource owner that is using the client application), is using the API?
When a user is using my official clients, they should obviously not have to grant any permissions - my clients should have all permissions. How would I distinguish between my official clients, and 3rd party clients when calling the API?
Here is what I understand, and would do so far. This is where I really need help - getting this done right.
Official Web app
- Client attempts to `GET /api/tasks/".
- API says "who are you? (HTTP 401)
- Official web app redirects to login form.
> Bob enters his credentials.
- .. now what? Get an authentication token? Cookie?
Since the web app is just a consumer of my API, how would I manage the logged-in state? Should the web app do that?
Should the web app have direct access to the users database instead of verifying credentials against the API?
I am using .NET (C#) primarily, but I'd love an approach that is applicable to, say, Node JS based API's as well.
How would you go about this? Especially the client flows are a problem for me. The reason I ask, is that I have read that you should not roll your own security solution unless absolutely necessary, so if there are any standard-ish guidelines for this, do let me know. :)
Take a look at the new web API 2 oAuth stuff.
Basically fire up a new web API project and ensure you select to change the authentication.
Then, it's a simple case of calling the register controller. This then creates a token for you which can then be sent in the header of each request for that user.
Check out the API calls using fiddler and create some mock up accounts.
It's been awhile, but I thought I would document what I ended up doing.
I use DotNetOpenAuth. I have a database with clients, and they have a Trusted field - if this is set, it lets the client use the password grant, which automatically grants all scopes that have been predefined for that client.
The 1st-party web app uses plain cookie auth - exposing the client credentials in JS would be too risky.
Related
I want to design a SPA which will have Frontend (React) and Backend-Rest API (Node.js, Express, Mongo DB). I am planning to have Single Sign-On in my application where users would be authenticating using MS-Azure AD, where a call would go to Azure AD from Frontend and in return I will get a token for that User which will be stored locally. After that, I want to call my rest API, for multiple GET, POST, PUT operations in the context of current user logged in on UI. Planning to deploy both frontend and backend on different servers so here I have two questions about securing my REST API.
CORS Implementation
User-Authentication on BE
Given the above requirements is it enough to have just CORS implemented or Do I need to again authenticate the User on BE?
Can somebody provide some best practice or experiences? Is there a lack in my “architecture”?
While CORS is definitely a consideration, it isn't Authentication (AuthN) or Authorization (AuthZ) which you need.
Depending on the number of users your application will have, how the back end will scale you might want to look at OAuth2.0 or stick with simpler session based auth but you will need something.
CORS on your back end will limit if a browser running an app on a domain other than yours to call your web services (it wont stop API requests from other tools).
AuthN - Your not logged in - go get logged in and come back to
me.
AuthZ - Controls what your users can and cant do. You might want to
enforce this at the resource level but you absolutely need to within
your business logic.
Further reading https://auth0.com/docs/authorization/concepts/authz-and-authn
Philippe from Pramgmatic web security has a free online course to get you started: https://pragmaticwebsecurity.com/courses/introduction-oauth-oidc.html Its very well paced and should give you some foundational knowledge. (It might let you write off OAuth for this use case but give it a go)
CORS will not perform any user authentication. You need CORS only when your client code is served from another domain than the backend you are talking too. If it is the same server to host static client files and backends REST endpoint, you don't need CORS. If you are unsure, then don't consider CORS at all and see if it works.
But you need authentication to know which user is which.
I'm working on a submission for a conference. I'd like to integrate DocuSign with Alfresco's Angular based developer framework and specifically the Alfresco Content App.
In order to keep things simple, I'd like to think about workflows that could be done 100% from the browser without any backend code of my own.
I suspect I could create a "Sign this document now" type action for any document found in the Alfresco UI. That could initiate an OAuth flow that would not require any backend services of my own.
I think I would need to put my integrator key into the SPA. This would then be visible to anyone using the app. From reading through docs, I'm unclear if it is OK to "leak" this key?
Are there other use cases I can implement in an SPA without adding backend services of my own? Things like, sending a doc out to be signed by one or more people? Or embedding a signing experience in the Angular UI?
I have seen the following series on the DocuSign blog:
https://www.docusign.com/blog/dsdev-building-single-page-applications-with-docusign-and-cors-part-1/
Having read through that and also the REST API documentation, I'm still unclear if it is even possible to implement something like this without any support from my own backend service.
I also have not found any place online where I can reach out to a developer evangelist from DocuSign to discuss my options. I believe DocuSign developers monitor SO, so figured this was the next best thing.
Great question. Browsers implement the Same Origin Policy. So, as I wrote in the blog series (see all three of my posts listed below), you will need a CORS gateway to make API calls from your Angular program running in the browser itself to the DocuSign system.
The good news is that creating a private CORS gateway isn't hard. See part 2 of the series:
Part 1. Introduction
Part 2. Building a private CORS gateway
Part 3. An example React SPA
Authentication
Your app will need an access token when it makes API calls to DocuSign. There are multiple techniques available to give your app the access token it needs:
Your app can, by itself, authenticate the user with DocuSign. In this case, because of the security issues--as you mentioned in your question--you do not use the OAuth Authorization Code Grant flow. Instead, you use the OAuth Implict Grant flow, which is designed for this use case. This flow is demonstrated in part 3 of the blog series.
You can implement the OAuth Authorization Code Grant flow in your server, and then create a private API between your server and your browser app to obtain the access token.
A private API
As an alternative to using CORS, you can just implement your own private versions of the DocuSign API methods on your server. Then your browser app would send a private_send_envelope request to your server. Your server would manage the access token, send the request to DocuSign, and relay the response back to your browser app.
This pattern is the same as your question about implementing a backend service. It will work fine but is not as elegant as implementing everything within your browser app. Depending on your immediate and future API needs by your SPA, this might be a good idea or not.
CORS support is the key
Until DocuSign has CORS support you'll need to build something on the backend. Either a CORS gateway (which only involves configuration, not software) or a private API gateway.
Please ask your DocuSign sales or technical contact to add your information to the internal DocuSign proposal for CORS support, PORTFOLIO-1100. This will help raise the priority of CORS support. Thanks.
Specific answers
Regarding:
I think I would need to put my integrator key into the SPA. This would then be visible to anyone using the app. From reading through docs, I'm unclear if it is OK to "leak" this key?
Answer: It is okay to add your integrator key (IK) to your browser app if and only if the IK is set for Implicit Grant usage (check the "Mobile App" checkbox on the IK's property sheet).
Having read through that and also the REST API documentation, I'm still unclear if it is even possible to implement something like this without any support from my own backend service.
Answer: at this time you will either need to implement a private CORS gateway or implement backend software.
I developed my Heroku app that exposes APIs only (no UI) and it works fine.
But how can I restrict the APIs to certain authorized/authenticated users only?
I absolutely need an authentication layer to protect the app APIs and prevent unauthorized accesses. A sort of login(user, psw) call to use before an external system can start invoking my API.
But I don't find any reference in the docs, it only says that these are the main security best practices:
Heroku SSL
Force the use of HTTPS
Trusted IP Range
Any idea?
That's something you'll need to implement at the application layer and not something that Heroku provides. At it's simplest you could implement basic auth in your app so that the user would pass them with their request, a more complex solution would involve user accounts and oauth etc etc.
You could implement all the authentication logic directly in your app.
Alternatively, take a look Auth0, which basically provides you with authentication and identity management as a service. You can easily add Auth0 to your Heroku app as a free add-on via the Heroku Elements marketplace.
They have lots of different use-cases and associated walk-throughs, and they offer a very generous free-tier.
From your requirements, it sounds like you might want to look at Auth0 Machine to Machine applications, using the OAuth2 Client Credentials Grant. With that, your external system(s) would basically need to authenticate with Auth0 using a Client Id and Client Secret (that you could generate in Auth0 and supply to them). Then, they would access your API with a JWT that you could easily validate in your app (Auth0 will provide you with generated code in many different languages for you to do that very easily). Your API will then reject requests without a valid JWT (by sending a "401 Unauthorized" response).
This may all sound a little intimidating at first, but it's really worth going through the relevant Auth0 "quickstart". They really go out of their way to try to make it as easy as possible!
I want to implement login and logout functionality and retrive user details like username and user role using Azure Active Directory.
We are using Docker to deploy Spring cloud microservices project on Azure cloud. Could you please suggest me steps to get user details?
Do we need to secure all microservices edge points using Spring cloud OAuth2 security using JWT or just we can secure one web microservice ? Do I need any permission ,specific user roles to implement this?
You can find Azure's documentation about OAuth 2.0 support for AAD here
https://learn.microsoft.com/en-us/azure/active-directory/active-directory-protocols-oauth-code
I've got an application that's using OAuth 2.0 with a different Authentication Server, and I'm about to see if I can use AAD as the Authentication Server. But, whatever ends up being your Auth Server, the rest of the application should be the same...
The Auth Server handles the log in (typically as a Single-Sign On pattern)
The Auth Server will return a Json Web Token (at some point, depending on the Grant Type being used to retrieve it)
The JWT should be included in each subsequent request to ensure the caller has authorization
From a Spring perspective, you'll need at least a SSO Client (denoted by the #EnableOAuthSSO annotation). If everything in hosted by that process, you'll need that JWT to call subsequent methods. If you have processes hosted in other processes, it's likely you'll want them secured as well. Using the #EnableResourceServer annotation will configure Spring Security to look for the JWT, just not attempt to retrieve one if the request does not have it.
Unless the endpoint is meant to be publicly accessible, you will want to secure it. Of course, I really don't know the context of your application, so this statement is purely an uninformed opinion based on zero knowledge of what you're trying to do with your application. Take it for what it's worth.
EDIT
This has become a little more complex than I originally thought. I have been able to write some code to dynamically retrieve the public key from Microsoft in order to validate the returned JWT.
But, the main issue is the fact the Azure AD supports Open Id Connect when acting as an Identity/Authentication Server. And, at the moment, spring-security-oauth2 doesn't support Open Id Connect.
I was able to make some small changes to the spring code, but I did ask the question to the Spring group and they are actively working on adding support for Open Id Connect. They hope to have a release two months (ish?).
For the short term, the oauth2 support doesn't support Open Id Connect. Given this is the protocol used by AAD, the current version of oauth2 won't work with AAD. That said, I will be happy to wait for the official support which shouldn't be too long.
At the moment we are building a web shop as a SPA application. All the SKU information is provided by a Web Api 2 service.
Of course the web shop is publicly available to every visitor, and currently there is only one user who can log in to manage the web shop: the administrator.
For the administrator we built in the basic authentication with the bearer token, as a lot of samples on the internet shows us, but now we need every user to log in before they can see any product. Not really what we have in mind for a web shop ;-)
What we would like to implement is that our Web Api is not available to the world but only for our SPA application. Every blog post or tutorial on authorization seems to assume that there is always a user that needs to log in, in our case there is only one user: the administrator.
The AllowAnonymous attribute makes specific API calls available to the world again, so that's also a dead end.
Basically it comes down to preventing any other apps (web or mobile) to fetch the data from our Web Api.
What would be the best and most secure approach to secure our Web Api without having the anonymous visitors of our web shop to log in?
Solution for now: Altough I'm not 100% happy with this solution, it will work for now. We implemented the OAuth Implicit flow with CORS enabled for specific domain.
You should take a look at the OAuth 2.0 client credentials flow. The client in OAuth speak is the application and not the user using the application. This way you can make sure only your SPA app can access the backend API.
The parts that only should allow access to the administrator, you can decorate with the [Authorize(roles = administrator)] attribute, which prevents any other roles from having access.
I think Json Web Token could help you with this. This article has more information about using Json Web Token for granular authorization of your web api.
OAuth 2.0 is inherently insecure, and solely relies upon SSL. It has no encryption, and most of the latest web api gurus are suggesting that it's dead. This again is relative to what you need the security for. If it's for a social SPA where the data isn't financial or medical, for example, and good enough SSL security is ok, then perhaps OpenID or OAuth2 is suitable.
A much better solution is to implement Identity 2.0 for the Web API authentication flow, and then utilize something like Hawk Protocol for HTTP MAC implementation. Check this out : https://github.com/webapibook/hawknet for an example.
For OAuth2 framework and a extensible solution, check out Thinktecture.IdentityServer3 on GitHub
For a lightweight .net 4.5 Web API Tokenization solution, check out Thinktecture.IdentityServer2 on GitHub.
Hope it helps.