This question is kinda complimentary to "Share credentials between native app and web site", as we aim to share secrets in the opposite direction.
TL;TR: how can we securely share the user's authentication/authorization state from a Web Browser app to a Native Desktop app, so the same user doesn't have to authenticate additionally in the Native app?
TS;WM: We are working on the following architecture: a Web Application (with some HTML front-end UI running inside a Web Browser of user's choice), a Native Desktop Application (implementing a custom protocol handler), a Web API and an OAuth2 service, as on the picture.
Initially, the user is authenticated/authorized in the Web Browser app against the OAuth2 service, using the Authorization Code Grant flow.
Then, the Web Browser content can do one-way talking to the Native app, when the user clicks on our custom protocol-based hyperlinks. Basically, it's done to establish a secure bidirectional back-end communication channel between the two, conducted via the Web API.
We believe that, before acting upon any requests received via a custom protocol link from the Web Browser app, the Native app should first authenticate the user (who is supposed to be the same person using this particular desktop session). We think the Native app should as well use the Authorization Code flow (with PKCE) to obtain an access token for the Web API. Then it should be able to securely verify the origin and integrity of the custom protocol data, using the same Web API.
However, it can be a hindering experience for the user to have to authenticate twice, first in the Web Browser and second in the Native app, both running side-by-side.
Thus, the question: is there a way to pass an OAuth2 access token (or any other authorization bearer) from the Web Browser app to the Native app securely, without compromising the client-side security of this architecture? I.e., so the Native app could call the Web API using the identity from the Web Browser, without having to authenticate the same user first?
Personally, I can't see how we can safely avoid that additional authentication flow. Communication via a custom app protocol is insecure by default, as typically it's just a command line argument the Native app is invoked with. Unlike a TLS channel, it can be intercepted, impersonated etc. We could possibly encrypt the custom protocol data. Still, whatever calls the Native app would have to make to decrypt it (either to a client OS API or some unprotected calls to the Web API), a bad actor/malware might be able to replicate those, too.
Am I missing something? Is there a secure platform-specific solution? The Native Desktop app is an Electron app and is designed to be cross-platform. Most of our users will run this on Windows using any supported browser (including even IE11), but ActiveX or hacking into a running web browser instance is out of question.
The best solution : Single Sign On (SSO) using Custom URL Scheme
When I was checking your question, I remembered the Zoom app that I am using in my office. How it works ?
I have my Gmail account linked to a Zoom account (this is account linkage, which is outside the scope of implementation). When I open Zoom app, I can choose the option to login with Gmail. This opens my browser and take me to Gmail. If I am logged in to Gmail, I am redirected back to a page that asking me to launch Zoom app. How this app launch happen ? The application register a custom URL scheme when app get installed and the final redirect in browser targets this URL. And this URL passes a temporary secret, which Zoom application uses to obtain OAuth tokens. And token obtaining is done independent of the browser, a direct call with SSL to token endpoint of OAuth server.
Well this is Authorization code flow for native applications. And this is how Mobile applications use OAuth. Your main issue, not allowing user to re-login is solved. This is SSO in action.
There is a specification which define best practices around this mechanism. I welcome you to go through RFC8252 - OAuth 2.0 for Native Apps.
Challenge
You need to implement OS specific native code for each application distribution. Windows, Mac and Linux have different implementation support for custom URL scheme.
Advice
PKCE is mandatory (in IETF words SHOULD) for all OAuth grant types. There is this ongoing draft which talks about this. So include PKCE for your implementation too.
With PKCE, the redirect/callback response is protected from stealing. Even some other application intercept the callback, the token request cannot be recreated as the PKCE code_verifer is there.
Also, do not use a custom solution like passing secret through another channel. This will make things complicated when it comes to maintenance. Since this flow already exists in OAuth, you can benefit with libraries and guidance.
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Update : Protecting Token Request
While the custom URL scheme solves the problem of launching the native application, protecting token request can be challenging. There are several options to consider.
- Bind native application launch with a secret shared from browser
When browser based client launch the native client, it can invoke a custom API to generate a secret. This secret acts like a one time password (OTP). User has to enter this value in native app before it obtain tokens. This is a customization on top of Authorization code flow.
- Dynamic client registration & Dynamic client authentication
Embedding secrets into public clients is discouraged by OAuth specification. But as question owner points out, some malicious app may register itself to receive custom URL response and obtain tokens. In such occasion, PKCE can provide an added layer of security.
But still in an extreme case, if malicious app registers the URL plus use PKCE as the original application, then there can be potential threats.
One option is to allow dynamic client registration at the first time of application launch. Here, installer/distribution can include a secret that used along with DCR.
Also, it is possible to use dynamic client authentication through a dedicated service. Here, the application's token request contains a temporary token issued by a custom service. Custom service obtain a challenge from native application. This may be done through totp or a cryptographic binding based on an embedded secret. Also it is possible to utilize OTP (as mentioned in first note) issued through browser, which needs to be copy pasted manually by end user. Once validated, this service issue a token which correlate to the secret. In the token request, native client sends this token along with call back values. This way we reduce threat vectors even though we increase implementation complexity.
Summary
Use custom URL scheme to launch the native application
Browser app generate a temporary secret shared with a custom service
At native app launch, user should copy the secret to native app UI
Native app exchange this secret with custom service to obtain a token
This second token combined with call back authorization code (issued through custom url scheme) is used to authenticate to token endpoint
Above can be considered as a dynamic client authentication
Value exposed to user can be a hashed secret, hence original value is never exposed to end user or another client
DCR is also an option but embedded secrets are discouraged in OAuth world
As you mentioned, using a custom protocol handler is not a safe way to pass secrets, since another app may handle your protocol and intercept that secret.
If you are imposing a strict constraint that the communication channel between the native app and the web app is initiated from the web app, and that the native app has not previously established a secure channel (e.g. shared secret which could encrypt other secrets), then it is not possible to safely transmit a secret to the native app.
Imagine if this were possible, then PKCE would be redundant in an OAuth 2.0 Code Flow, since the server could have safely transmitted the access token in response to the authorization request, instead of requiring the code_verifier to be provided with the grant when obtaining the access token.
Just got the following idea. It's simple and while it doesn't allow to fully automate the setup of a secure channel between Web Browser app and the Native app, it may significantly improve the user experience.
We can use Time-based One-Time Password algorithm (TOTP). In a way, it's similar to how we pair a Bluetooth keyboard to a computer or a phone.
The Web Browser app (where the user is already authenticated) could display a time-based code to the user, and the Native app should ask the user to enter that code as a confirmation. It would then use the code to authenticate against the Web API. That should be enough to establish a back-end channel between the two. The life time of the channel should be limited to that of the session within the Web Browser app. This approach might even eliminate the need for a custom protocol communication in the first place.
Still open to other ideas.
You could try driving the synchronization the other way:
Once the user is authenticated into the web app, launch the native app from the web app via the custom URL scheme.
If the native app is not authenticated, connect securely to the backend over HTTPS, create a record for the native app, retrieve a one time token associated with that record and then launch the web app in the user's browser with the token as a URL parameter.
Since the user is authenticated in the browser, when the server sees the token it can bind the native app's record with the user account.
Have the native app poll (or use some other realtime channel like push notifications or a TCP connection) the server to see if the token has been bound to a user account: once that happens you can pass a persistent auth token that the native app can store.
Did you think about using LDAP or Active Directory?
Also OAuth2 could be combined, here are a related question:
- Oauth service for LDAP authentication
- Oauth 2 token for Active Directory accounts
SSO should be easier then too, furthermore access-rights could be managed centralized.
Concerning general security considerations you could work with two servers and redirect form the one for the web-application to the other one after successful access check. That 2nd server can be protected so far that a redirect is required from the 1st server and an access check could be made independent again but without need to login another time, might be important to mention here the proposed usage of Oracle Access Manager in one linked answer for perimeter authentication.
This scenario with two servers could be also hidden by using a proxy-server in the frontend and making the redirects hidden, like that data-transfer between servers would be easier and secure too.
The important point about my proposition is that access to the 2nd server is just not granted if anything is wrong and the data are still protected.
I read here some comments concerning 2FA and some other ideas like tokens, surely those things increase security and it would be good to implement them.
If you like the general idea, I'm willing to spend still some time on the details. Some questions might be helpful for me ;-)
EDIT:
Technically the design in detail might depend on the used external authentication provider like Oracle Access Manager or something else. So if the solution in general sounds reasonable for you it would be useful to elaborate some parameters for the choice of a external authentication provider, i.e. price, open-source, features, etc.
Nevertheless the general procedure then is that the provider issues a token and this token serves for authentication. The token is for unique one-time usage, the second link I posted above has some answers that explain token-usage very well related to security and OAuth.
EDIT2
The Difference between an own OAuth2 / OIDC server and a LDAP/AD server is that you need to program everything by yourself and can't use ready solutions. Nevertheless you're independent and if everything is programmed well perhaps even a bit more secure as your solution is not public available and therefore harder to hack - potential vulnerabilities just can't be known by others. Also you're more independent, never have to wait for updates and are free to change whatever you want at any time. Considering that several software-servers are involved and perhaps even hardware-servers the own solution might be limited scale-able, but that can't be know from outside and depends on your company / team. Your code base probably is slimmer than full-blown solutions as you've only to consider your own solution and requirements.
The weak point in your solution might be that you have to program interfaces to several things that exist ready for business-frameworks. Also it might be hard to consider every single point in a small team, large companies could have more overview and capacity to tackle every potential issue.
I have a website which uses an identity server to authenticate a user, though OIDC, I think. Inside the Xamarin Forms application, I have a facility to log in a user through an identity server via a token.
The website itself uses cookies to handle access tokens which difference to the application. (Note: the website was not written by me). I have so many features to write, so I decided to use WebView to handle those features using React, etc., so I don't need to rewrite the code in native and easy to manage at runtime when people using the application.
What is the logic behind having the mobile application log into the authorized page silently without the user needing to authenticate within the WebView?
Is it possible to handle this scenario?
On Android you can use the CookieManager to add/remove cookies that your private instance of Webview will use.
On iOS, UIWebView has NSHTTPCookieStorage and on the newer WKWebView (11+) you have WKHTTPCookieStore
I have a Web API registered in and secured with Azure AD. I am having a ASP.NET Core MVC Web application which consumes this API service. The controllers are automatically authenticated by use of Authorize attribute and I can get accessToken for current logged in user.
I am writing unit test for the UI web application. Can anyone help me with how to get Azure AD access token from unit test methods? Thanks in advance.
Since your unit tests probably want to run without user interaction, you need to use a different authentication flow.
Some APIs support username/password authentication, where your code has access to a set of credentials that can be used (see http://www.cloudidentity.com/blog/2014/07/08/using-adal-net-to-authenticate-users-via-usernamepassword/).
If you want something a little more secure, you can use certificate based authentication. It is somewhat more complicated to setup and implement (https://github.com/Azure-Samples/active-directory-dotnet-daemon-certificate-credential), but gives access to more APIs (e.g. Exchange Web Services user impersonation requires it).
What is the recommended way to restrict my django rest framework APIs to be available to my mobile and web apps only ? I'm using django-rest-auth to authenticate my users. There are some APIs that can be accessed anonymously. But I need to make sure that all the APIs are available only through my apps (mobile and web).
Any help/tutorials are highly appreciated.
Thank you
You need to setup the authorization scheme at the configuration level to restrict it to your mobile / web app only and explicitly set the public ones at the class level. See http://www.django-rest-framework.org/api-guide/permissions/#setting-the-permission-policy about implementation details.
Because all requests can be sniffed you can't use any Secret-key or check for HTTP origin (it can be faked easily).
For mobile you can try using secret-key generator with some special algorithm. Fro example MD5(current_time + your_secret_phrase). Then you will be able to verify that code is acceptable. It will make using your API almost impossible for sniffers.
But for Web you can't do much. All headers can be faked. The only way - user authentication.
You can, of course, use Secret-key and change it every month/day/hour. But is it worth it?
We're developing an API and a single page application (that is one of more possible future consumers of it).
We already started on the web API, and basically implemented a system very similar to the one John Papa made in his course on pluralsight, named "Building Single Page Apps (SPA) with HTML5, ASP.NET Web API, Knockout and jQuery".
We now need to implement authentication and user managing in this application and need to find the easy way out to implement this in as little time as possible as we are in a hurry.
We realized the SPA template included in the ASP.NET update had very similar features to our needs, but we wonder what the best approach to implement a similar feature in our existing code.
We are novice developers, as you might figure.
Is it possible nstall some packages using the package manager, and voila, a simple membership and OAuth auth option be readily available?
Our use case is that we need to protect some resources on our API based on roles, and that one should be able to log in using a username and password, but also log in using ones facebook, google, or twitter account.
Found an interesting talk regarding the subject here: https://vimeo.com/43603474 named Dominick Baier - Securing ASP.NET Web APIs.
Synopsis: Microsoft’s new framework for writing RESTful web services and web APIs is appropriately enough called ASP.NET Web API. As the name applies, this technology is part of ASP.NET and also inherits its well-known security architecture. But in addition it also supports a number of new extensibility points and a flexible hosting infrastructure outside of IIS. There are a number of ways how to do authentication and authorization in Web API - from Windows to usernames and passwords up to token based authentication and everything in between. This talk explores the various options, and puts special focus on technologies like claims, SAML, OAuth2, Simple Web Tokens and delegation.
We eventually went with the SPA template, doing authentication on the API (separate MVC part).
Then the API would generate a unique token and redirect the user to the front-end with the token in url parameters.
The front-end then needs to send this token on every subsequent request.
Have a look here - Identity Server done by the security experts. This is all you need in one package.
In terms of OAuth, you would need to use Client-Side Web Application flow which the access token is issue immediately to the client and can be used.