So I was previously using B2C for authentication. I had gotten my functions configured so that they required authentication via B2C and everything worked fine. If you tried calling them without being authenticated, nothing happened (or rather, you got an error).
I want to use a 3rd party provider, like Auth0, because there's some limitations and issues with B2C at the moment that seem to only very slowly get worked on. Anyway, I'm not sure how I'm supposed to configure my functions for this. I went to the Authentication/Authorization settings blade and I've set "App Service Authentication" to "on", "Token Store" to "On", and "Action to take when request is not authenticated" is set to "Allow Anonymous requests (no action)". Under "Authentication Providers" all of them are set to "Not Configured'. My first problem is that at this stage, if I call any of my functions using say Postman, I can call them just fine without any authentication information whatsoever. It's as if they're totally unprotected.
I'm not sure what I'm supposed to set so that my functions require authentication BUT with a 3rd party, not with the 5 default listed providers.
Or am I thinking about this the wrong way? Is the solution instead to allow unauthenticated access to my functions, but in the functions themselves do my token validation/etc rather than relying on whatever it is that Microsoft does behind the scenes to validate the request (like when you use B2C)?
Your final thought is on the mark, if you're bringing a 3rd party auth provider that is unsupported by App Service Authentication the best choice is to allow unauthenticated access and validate the request yourself.
However, keep in mind that any input bindings will run before your function code executes (and auth validation occurs), so you need to be careful with using input bindings and custom auth.
Update: App service authentication does have 'bring your own auth provider' on the backlog, so hopefully this scenario will be better supported soon.
Related
I have a .Net 5 Web API hosted on Azure App Service.
The API has three Background services running as hosted services, which perform long running processes such as bulk emailing and SMSing, as well as other functionality that runs once a day on a timer.
I am thinking about moving out these hosted/background services into separate Azure Functions, which I would then call / trigger from my API via an HTTP request (except for the one that runs on a timer)
My concern is regarding authentication. How does that work with Azure Functions? Currently, my Web API is using Auth0 as the authentication server. So, when the user uses the front-end web app (Angular), he logs in (via Auth0's login form) and then the front-end retrieves an access/bearer token from AUth0, which it then includes in every call to the API (in an Authentication header).
Now, obviously I don't want just anyone to be able to call the Azure Functions - only my Web API should be able to do so. But how does that work? Does the API need to forward the access token it received from the front end to the Azure Function when calling it? Or is there something I need to set up in Azure Portal to tell it that my API must be allowed access to the Azure Function (and block any requests from any other origin)?
I've never used Azure Functions or even WebJobs before, so I'm a bit lost.
Thanks
When creating an HTTP-triggered Azure Function, by default it is set to have authorization level = Function, which means that any app trying to invoke that function via its URL needs to know the specific access key that is generated for that function upon creation.
In your example, your web API would store that function's invocation URL and access key in its configuration, and invoke your function with that key. Since the key remains entirely server-side on Azure, nothing else can access it, so it's completely secure.
Depending on your requirements, you can then also layer other types of authorization/authentication (e.g. bearer token) on top of the access key mechanism, or use those instead of access keys (by setting the function to allow anonymous access).
For maximum security, I would recommend using both the function access key as a first step to ensure that nobody except your apps can successfully invoke the function, and then passing along and authenticating the bearer token to ensure that the app trying to invoke that function is indeed permitted to do so.
Just be aware that Azure Functions is a slightly different beast to standard ASP.NET Core, particularly in regards to middleware which it doesn't really support yet, so you'll likely need to roll your own code for reading the bearer token from the incoming HTTP request's headers, and verifying that it's valid.
Reference: https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-http-webhook-trigger?tabs=csharp#authorization-keys
For this requirement, you just need to enable "Authentication/Authorization" of your function app.
Follow the steps in the screenshot above and when you click the forth red box, choose "Express" tab and click "ok" at the bottom of the page without do anything. It will create an application in your Azure AD which has same name with your function app.
After that, when you request the function app url in browser, it will ask you to login.
For more details of the steps, you can refer to this document.
Hury's guidance is best - you want to avoid using API keys on your production functions and use this just for testing. Official guidance is here:
https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-http-webhook-trigger?tabs=in-process%2Cfunctionsv2&pivots=programming-language-csharp#secure-an-http-endpoint-in-production
Configure your Functions for AuthorizationLevel.Anonymous, and require Authentication on your Function as Hury describes. This will not only require end users to authenticate, but supports System Assigned Managed Identity when your function is called from other App Services. Less keys to vault or configure means less to steal.
Depends on what you mean by authentication.
If you just want to secure your functions you can use the authorization level = function.
However, if you need authentication with login, and you need to know the user making the request, you have to use bearer token with OpenIDConnect server.
Always use stateless authentication regardless your method.
I've implemented an ASP.NET Web API app as an Azure App Service. It has an App Registration, everything works as expected. I can hit the API from a browser and see all the JSON it returns. Now what I want to do is ensure that nothing except one or more applications from a set list can actually get anything from this endpoint. The applications needing access will all be custom ones in my organization/tenant. With all the flexibility and options, I'm having a very hard time determining what I need to do to lock the API down in this way.
I was envisioning having some client secrets the API knows about, and let the authorized applications supply them. Other methods would certainly be acceptable.
I'm certain this must be a duplicate question, but due to the plethora of information out there, and the myriad techniques for running applications on Azure, I can't seem to find just the right solution for my simple case.
It sounds like you have implemented interactive browser redirect-based authentication on the API.
Instead, you should implement JWT authentication on the API.
Then in Azure AD you can define permissions that can be granted to client applications.
In that way you can control which app can do what.
https://joonasw.net/view/azure-ad-authentication-aspnet-core-api-part-1
https://joonasw.net/view/azure-ad-authentication-aspnet-core-api-part-2
https://learn.microsoft.com/en-us/azure/active-directory/develop/scenario-protected-web-api-overview
https://learn.microsoft.com/en-us/azure/active-directory/develop/v2-permissions-and-consent
Might seem a silly question, but Microsoft's documentation isn't very beginner friendly, I think. It uses as examples "http://localhost:31544" for the sign-on url and "http://MyFirstAADApp" for the redirect URI, but although I understand what a local host is I can't figure out what exactly the numbers on it are and how I define them for my application, and absolutely zero clue of what the redirect URI is supposed to do for a native application and how should I define a URI for my own.
To be more clear on what kind of app I'm trying to add, I merely want to acess the Office 365 management API tools and get some data from it, so I imagine a native app would fulfill my needs for now. Registering the app on Azure AD is required to do so according to Microsoft's documentation.
So expanding on the title, how to define an URI for my native app is what I would mainly like to know. Some further clarification on what exactly is the purpose of this URI as well as to how to use and/or define a localhost URL for an Web app would also be much appreciated.
I know this is ancient, but I don't see a satisfying answer here, and maybe someone will come across this and find it useful. To answer the question asked, unless you're going to work outside of the default MSAL handling of the server responses, and I don't expect you would from your description, I'd just go ahead and use the default:
https://login.microsoftonline.com/common/oauth2/nativeclient
When you go into the Azure AD portal, go to your application and, from the Overview, select the "Set RedirectURL" option, you'll add a platform and select the "Mobile and Desktop Applications" and you'll be provided with the choice of 3 URLs to choose from. My understanding is this is just there for custom handling of authorization tokens and is telling MS where to send those tokens. The MSAL library functions seem to use this link as well, so they're probably handling this in the backend.
I agree with the OP though, the MS docs are severely lacking for newcomers and I wasn't able to find an end-to-end description of what needs to happen to get, in my case, a desktop application to send email through Office365 using 2FA. I would forge ahead as best I could until I hit the next error, then explore that, sort it, then slam into the next one. Rinse and repeat. This was made extra tedious as I had to go through a 3rd party IT group to get the 2FA access codes every time I wanted to test.
Best of luck, hope this helps someone!
how to define an URI for my native app is what I would mainly like to
know.
You should provide a Redirect URI that is unique to your application as it will return to this URI when authentication is complete.
In your application, you will need to add a class level variables that are required for the authentication flow, include ClientId and Redirect URI.
Here is the diagram:
Native application makes a request to the authorization endpoint in Azure AD, this request includes the Application IP ,Redirect URI and application ID URI for the web api.
After user signed in, Azure AD issues an authorization code response back to the client application's redirect URI. After that, the client application stops browser interaction and extracts the authorization code from the response.
Then the client app use this code to sends a request to Azure AD's token endpoint. upon successful validation, Azure AD returns two tokens.
Over HTTPS, the client app uses the returned JWT access token to add the JWT string with a “Bearer” designation in the Authorization header of the request to the web API. The web API then validates the JWT token, and if validation is successful, returns the desired resource.
More information about it, please refer to this article.
For native you can set redirect to be equal to the Application ID URI, which now defaults to look like //app:{ApplicationId}
Redirect uri be starts with SSL URL, so select your project, enable SSL URL and use this auto generated SSL URL (for example : https://localhost:port#) as redirect uri , same to be updated in the azure app registration as additional redirect URIs
I'm making an iOS/Android app using Xamarin (not Xamarin.Forms, just regular Xamarin). I'm using the shared library set up rather than PCL. I want my app to call an Azure function but I'm unsure of the safest/best way to handle this. I have it set to "Function" for the "Authorization level". The test URL includes the "?code=..." portion in it. I was under the impression that if I put that in my C# code with the "code" value exposed that it was considered a bad idea from a security perspective.
I'm lost as to the safest/best way to deal with this. I've read that setting it in app.config is also a bad idea. I found some references for a web app that suggest using the connection strings that are available in the azure portal, but since this isn't a web app, I'm unsure of how I'd actually retrieve those values in my code (or if that's even possible).
So how would you suggest I handle setting the value for "code" so that I can call my function and avoid a security problem?
UPDATE: Providing more info as per request:
I'm using MSAL to authenticate my users with a B2C active directory. I already have that part working and have received a token authenticating the user.
I also just now enabled authentication in my functions.
I was under the impression that to call my function from my mobile client I had to make a new HttpRequestMessage. I'm unsure of then what I'd place in it to pass my token along.
Just to make sure I understand, your concern is about embedding secrets (the ?code=XXX value) in your iOS/Android app, correct? If so, yes, this is generally considered bad security practice. It's best to assume that anyone who can download your app will have the ability to discover these secrets and use them any way they want.
The recommended way to authenticate with a backend service, such as Azure Functions, from a mobile device is to use interactive authentication - i.e. some kind of OAuth flow. You can build it yourself, or you can use the built-in functionality of Azure Functions and Azure App Service to help you (Azure Functions is built on top of App Service). Here is a resource which might be useful:
https://learn.microsoft.com/en-us/azure/app-service/app-service-authentication-overview
https://contos.io/working-with-identity-in-an-azure-function-1a981e10b900#.vcjit3ntw
The API Key (code) is indeed not meant to be used by clients you distribute externally, so it shouldn't be used by your mobile app.
The most straight forward option here would be to use the built in App Service Authentication features with Azure Functions and implement an authentication flow in your app, which would allow you to securely authenticate the user.
Sharing more information about your scenario may help identify alternatives.
I would like to secure my Azure WebApi with 3rd party providers (FB, G+... I basically just need a valid email). Was looking at Auth0 and seems like it will do the thing paired with Jwt middleware in web api project, but I was wondering if the same can be done using Azure only.
Azure Web App authentication confused me a bit - it does not seem to give anything to my Asp.Net web app. I still have to configure all the middleware in Startup.cs and the app still works fine if I completely turn authentication off.
I could do the same thing Auth0 does - issue my own Jwt tokens based on access tokens from FB or G+ - but would like to avoid that.
Could you please point me to the right direction?
You have a couple options:
App Service Authentication
Configure the authentication via middle ware
App Service Authentication
The App Service Authentication does not require any code inside your application because your App Service has a gateway that inspects request for authorization. Depending on the setting you can either secure the entire site or secure individual resources (by using the [Authorize] attribute on the endpoint in MVC/WebAPI).
With the latest release you can control authorization on a site by site basis including manually triggering the sign in by navigating the user to the <yoursiteurl>/.auth/login/<provider>. By defualt the token store is enabled so you can make a request to <yoursiteurl>/.auth/me and get back information from the provider.
Middleware Authentication
This is the default way authorization happens in the Single Page ASP.NET Template. The middleware authentication uses OAuth/OpenId to secure the resources. This option does it at the application layer instead of at the gateway. If you are using ASP.NET Identity (from the single page project template) the email from the persons log in will automatically be stored in the Users table. The tutorial in the link above gives lots of details on how to get it working.
Make sure you use the [Authorize] attribute to trigger the Authorization in either case.
Hope that helps you get started in the right direction.