I have a microservice architecture, where one Single Page Application accesses three different APIs:
I am securing those APIs via the Microsoft Identity Platform and therefore I also need service principals.
My first approach matches with all the examples I found on blogs or in the MS docs.
In this case I have one app registration for the client app and three additional ones for the APIs:
This has the following impact:
Each API has its own audience.
I get four service principals for each application.
I get three different places where I have to administrate the user assignments to roles. (for example: User A can read assets from API A etc...)
This works, but comes also with some problems:
The other admins that are managing which user is allowed to do what are confused about three different places they have to assign roles. It would be nicer to have one central place.
The roles of the users are not placed in the ID tokens, because only roles of the client application would go there... but I do not want to assign permissions in the client app again.
If API A wants to call API B or C, I need two access tokens for other APIs.
This lead me to a second idea:
Here I have one registration for all 3 APIs. This already solves problem 1 and problem 2. But it also gives me a strange feeling, because I never found other people doing so.
Also my ID tokens are not telling me the roles, so to fix this, I could even go another step further to a single app registration for everything:
Now one registration exposes an API and consumes this API also. Something what is possible and seems to solve my problems. I even get all roles for the users in my ID tokens AND in my access tokens now.
However, this is contradictive to all other examples I found.
Which disadvantages does the last solution have?
Which of the three approaches should I chose?
Which disadvantages does the last solution have?
One thing that comes to my mind is that you want API A to be able to edit data in e.g. MS Graph API, so you give it the app permission to Read/Write Directory data.
Now with the shared app registration this permission has also been given to API B and API C.
So the principle of least privilege may be violated in the second and third options.
But it does make it easier to manage those APIs as you noticed.
The third option does open up the door for the user to acquire access tokens to any APIs that you might want to call on behalf of the current user from your APIs.
So if you wanted to API A to edit a user through MS Graph API on behalf of the user, you'd have to require the read/write users delegated permission (scope) for your app.
This would allow the user to acquire this token from your front-end as well, even though that is not intended.
Now they would not be able to do anything they wouldn't otherwise be able to do since the token's permissions are limited based on the user's permissions, so this might not be a significant disadvantage.
Which of the three approaches should I chose?
As with many things, it depends :)
If you want absolute least privilege for your services, option 1.
If you want easier management, I'd go with option 3 instead of 2.
There was that one thing I mentioned above about option 3 but that does not allow privilege escalation.
Related
Assume my company is offering 2 applications, say Mail and Calendar.
Both applications are using OAuth 2 to secure access.
Now Calendar wants to access data from Mail. If those were applications from two different vendors it would be natural for Calendar to ask the user to authorize it's access to Mail etc.
But since the applications come from the same source I'd like them to be able to share data without the user having to explicitly give permissions.
Or to put it differently: I have ID/Access/Refresh tokens for Calendar. How can I exchange them for an Access Token for Mail without bothering the user?
How can this be done in OAuth 2? I control both the applications and the Identity Provider.
The only solution that comes to my mind is for both Mail and Calendar to be the same Application, but that doesn't seem right (and has other issues, e.g. if you want to restrict someone's access to one of them). I could also implement special access outside of OAuth 2 but that is even worse.
A real world example would be Gmail and Google Calendar. They both present OAuth 2 interface to the outside world, but you don't have to allow them to talk to each other.
PS. References to white papers or cases studies would be appreciated
SEPARATED CLIENTS
By default in OAuth you would register multiple clients which get their own tokens. You would then use Single Sign On when navigating between them the first time:
Client ID: app1
Scope: openid scope1
Redirect URI: https://app1.mycompany.com
Client ID: app2
Scope: openid scope2
Redirect URI: https://app2.mycompany.com
If user consent is involved the user has more choice this way of how they grant access to their personal assets.
COMBINED CLIENT
You could potentially combine these into a single entry like this. Note that there is usually a hosting prerequisite of a single base domain in order for token / cookie storage to work:
Client ID: combinedapp
Scope: openid scope1 scope2
Redirect URIs: [https://app1.mycompany.com https://app2.mycompany.com]
PROS AND CONS
The first option is cleanest most of the time, since you avoid tokens with access to too much data. The second option can make sense for related micro-UIs that are really a single app with the same permissions.
APIs AND SCOPES
To share data across apps, companies build API endpoints. You can then have multiple apps that each use scopes representing multiple business areas. See the Scope Best Practices article as a starting point for designing authorization. Eg user logs into calendar app with scopes openid calendar mail - and therefore can get mail data also.
I'm writing an application that will be the backend for a react website. The website is to be used by our customers, but we will fully control the permissions of the user. We have decided to use Azure AD to secure requests, but will also be exposing the API for end users to use directly if desired.
My understanding is in Azure AD I will have to create an application that will allow web based implicit authentication (for the react site), as well as a native application that will allow a dameon based application to authenticate to the API.
This I believe means I will have two audience ids in my application.
I'm trying to get claims to include groups, and I can see if I edit the meta data of both applicaitons in azure AD to include "groupMembershipClaims": "SecurityGroup" I can get claims with the group IDs in, but no names.
I think I can also use appRoles to set roles the application uses, but I've yet to get that to come through as claims in the JWT, but I'm assuming it can be done, however I'd need to setup the roles on each applicaiton, then add the user twice which isn't really ideal. I also think that because my app is multi-teanated that external users could use this to set their own permissions, which isn't what I want to do.
Sorry I'm just totally lost and the documentation is beyond confusing given how frequently this appears to change!
TLDR: Do I need two applicaitons configured in azure ad, and if so whats the best way to set permissions (claims). Also is oAuth 2 the right choice here, or should I look at open id?
Right away I gotta fix one misunderstanding.
Daemon apps usually have to be registered as Web/API, i.e. publicClient: false.
That's because a native app can't have client secrets.
Of course the daemon can't run on a user's device then.
Since that's what a native app. An app that runs on a user's device.
This I believe means I will have two audience ids in my application.
You will have two applications, at least. If you want, the back-end and React front can share one app (with implicit flow enabled). And the daemon will need another registration.
I'm trying to get claims to include groups, and I can see if I edit the meta data of both applicaitons in azure AD to include "groupMembershipClaims": "SecurityGroup" I can get claims with the group IDs in, but no names.
Yes, ids are included only. If you need names, you go to Graph API to get them. But why do you need them? For display? Otherwise, you need to be using the ids to setup permissions. Names always change and then your code breaks.
I think I can also use appRoles to set roles the application uses, but I've yet to get that to come through as claims in the JWT, but I'm assuming it can be done, however I'd need to setup the roles on each applicaiton, then add the user twice which isn't really ideal. I also think that because my app is multi-teanated that external users could use this to set their own permissions, which isn't what I want to do.
Your thoughts for multi-tenant scenarios are correct. If you did want to implement these though, I made an article on it: https://joonasw.net/view/defining-permissions-and-roles-in-aad.
Why would you need to setup the roles in multiple apps though? Wouldn't they only apply in the web app?
If the native app is a daemon, there is no user.
Overall, I can see your problem. You have people from other orgs, who want access to your app, but you want to control their access rights.
Honestly, the best way might be to make the app single-tenant in some tenant which you control. Then invite the external users there as guests (there's an API for this). Then you can assign them roles by using groups or appRoles.
If I misunderstood something, drop a comment and I'll fix up my answer.
Azure AD is of course a powerful system, though I also find the OAuth aspects confusing since these aspects are very mixed up:
Standards Based OAuth 2.0 and Open Id Connect
Microsoft Vendor Specific Behaviour
ROLE RELATED ANSWERS
This is not an area I know much about - Juunas seems like a great guy to help you with this.
OAUTH STANDARDS AND AZURE
I struggled through this a while back for a tutorial based OAuth blog I'm writing. Maybe some of the stuff I learned and wrote up is useful to you.
AZURE SPA AND API CODE SAMPLE
My sample shows how to use the Implicit Flow in an SPA to log the user in via Azure AD, then how to validate received tokens in a custom API:
Code Sample
Write Up
Not sure how much of this is relevant to your use case, but I hope it helps a little on the tech side of things...
I'm working on a service that provides smart (hopefully) integration of different services supporting OAuth 2.0. The focus of our tool is on team work flow improvement, so we're combining Slack, GitHub, Asana (issue tracker), Cezanne (hr tool), etc.
We have ui and backend that work with all those tools (user is authorised to all of them, so I have required access and refresh tokens). We need to be able to hide different parts of the ui depending on person's role in a specific tool. Let's take GitHub as an example. The user can be a repository owner, contributor, company owner (for business account), etc, so those user might need different ui based on their rights.
Originally I was hesitant implementing authorisation on my own (another custom authorisation system is the last thing this world needs), I wanted to take advantage of other services' authorisation mechanisms and just create a lightweight wrapper around them. It seemed like a reasonable idea at first, but I can't figure out how to implement it and Google doesn't give valuable advice which means: 99.99% I'm trying to do something stupid, 00.01% I'm trying to do something rare/innovative.
I hoped to take advantage of OAuth 2.0 but it doesn't seem to support what we need. The closest thing is scopes but it doesn't look very relevant to our scenario.
The only idea I have for now is to create our own authorisation system and integrate other services using kind of reverse engineering. So I would request user's GitHub account details using API and apply him roles in our system appropriately: Owner for repository A, contributor for repository B, owner of company C, etc. I will have to reverse-engineer the permission for each role (i. e. repository owner can not change company name). And we would have to keep user roles for each service: so instead of typical Admin/User/Manager/etc. we will get: OwnerOfGitHubRepository (for repositoryA), ManagerOfAsanaTeam (for team B), etc.
It would be awesome if OAuth 2.0 services had an endpoint that would return the permissions available for a current user.
I'm not a security engineer, so I might be missing something obvious. So wanted to ask you guys for advice before investing into the implementation mentioned above.
The word, "authorization", is used in two different contexts.
In one context, authorization means "who has what permissions". Solutions for this authorization is "identity management".
In the other context, authorization means "who grants what permissions to whom". Solutions for this authorization is "OAuth".
In some cases, you may have to handle these two authorizations simultaneously. See this question and this answer for details.
You tagged your question with identityserver4.
This Issue for identityserver3 from last year may interest you.
But I'm afraid most providers don't support this oauth2 profile (yet).
UMA seems to be an oauth2 way to enable fine grained authorization, but may not be the best solution.
I'm trying to understand OAuth best practice implementation strategies for systems requiring access to protected resources backed by different authorization servers. The default answer is to use the access tokens provided by each authorization service and write the logic to store them on an as-needed basis, but the use case of systems requiring multiple, federated protected resources seems common enough that there might be a protocol/framework-level solution. If so, I haven't been able to find it.
Here's a hypothetical example to clarify:
I'm a user with an account on Dropbox, Google Drive, and Boxx. I'd like to make a backend API to report the total number of files I own across all three systems, i.e., Result = FileCount(Dropbox) + FileCount(Drive) + FileCount(Boxx). How to I organize the system in such a way that I can easily manage authorizations? A few cases:
Single-account: If I only have, say, a Drive account, the setup is easy. There's one protected resource (my folders), one authorization server (Google), and so I only have one token to think about. By changing the authorization endpoints and redefining the FileCount function, I can make this app work for any storage client I care about (Dropbox, Google, Boxx).
Multi-account: If I want to aggregate data from each protected resource, I now need three separate authorizations, because each protected resource is managed by a separate authorization server. AFAIK, I can't "link" these clients to use a single authorization server. As a result, if I have N protected resources backed by N authorization servers, I'll have N access tokens to manage for a given request/session. Assuming this is true, what provisions do software frameworks provide to handle this (any example in any language is fine)? It just seems too common of a problem not to be abstracted.
The closest related question I can find is probably this one. The accepted answer seems completely reasonable: one application should not be able to masquerade as another without explicit consent. What I'm looking for is (I think) slightly different: some standard methodology/framework/approach to managing multiple simultaneous access tokens per session. I've also wondered about the possibility of an independent authorization server that can proxy the others as needed and manage the token bookkeeping (still requiring user consent for each), but I think this amounts to the same thing.
Thanks in advance.
I'm working for a non-profit that is trying to create a collection of services that will allow them to do a few things:
Create/Manage Users
Create/Manger Competitions
Create/Manager Events(a Competition is made up of many Events)
Logistics
Etc.
Here are some of the requirements:
Host on Azure
Accounts are created using the user's own email address (can be any domain)
Each service must be independent of each other
System should be accessible from anywhere(browser, mobile app, etc.)
Once a user logs in, access to other systems should be available(if needed or depending on permissions)
-services can talk to each other(we've successfully done a POC on this using Azure Active Directory)
I've spent some time researching the possible ways to tackle this, including looking at articles like this:
http://bitoftech.net/2014/10/27/json-web-token-asp-net-web-api-2-jwt-owin-authorization-server/
It sounds like JWT is the way to go, but I want to make sure that this architecture approach lends itself to flexibility down the road. I'm willing to learn/user any technology as long as it plays along .Net, Web Api, and MVC.
My initial idea was to set each "system" as a Web API, which is pretty straightforward. My concern is authentication/authorization. The million dollar question then becomes:
How can I authenticate a user on a browser/mobile/desktop app and then make use of the other services(APIs), where each service can verify if the user is authenticated independent of other services.
For example, lets say I am using the web app(browser) and register as a user(using User service) in order to register for a competition(Competition service). what kind of technologies/architecture would need to be used for both services to use the same authentication mechanism?
I am not new to MVC or Web API but I am to a scenario like this, so all help or advice is greatly appreciate it. For any that are interested, this is the non-profit: http://worldjumprope.org/
They are doing some cool stuff in terms of outreach and spreading the love for jump rope. Their goal is to be able to help people all around the world and provide a way to for them to come together and compete. They've been doing it for years, growing each year, all for free and out of pure passion for the sport. Help me help them!
Azure Active Directory can help you with your need.
About the security/Auth mechanism, simply put, it is like you get a token from Azure Active Directory to be able to use it to do authentication for a certain Audiences/Tenants.
And in your architecture, when you acquire a Token, you can specify if you are going to use it against a certain audience or it will work for a list of audiences or all audiences in a specific tenant or in a multi tenant scenario.
Here is a link to a video about AAD Single Sign on:
https://azure.microsoft.com/en-us/documentation/videos/overview-of-single-sign-on/
You can download the AAD Solutions arcutecture from here:
http://www.microsoft.com/en-us/download/details.aspx?id=45909
Also maybe worth looking at Identity Server - https://github.com/IdentityServer/IdentityServer3.
Same concept as Azure AD in terms of tokens, but perhaps with greater options for what you choose as a data store for your user information.
There are lots of demos and source code on the site, particularly around the different types of authentication flow \ service to service authentication