API: How to secure access from non-related users? - amazon-web-services

I am developing a REST API. In my mobile application we have multiple user roles, they all use the same API. Think the roles are like customer, supplier, and admin. The API is using tokens, making sure everyone need to be logged in and should send the token to the API.
However, if someone has the token somehow, he can easily any information belong to any user. For an example, using the token of customer A, we can view the information of customer B, C` and so on.
Not only that, we can also access the API calls dedicated for the admins using the above mentioned token.
this is what I thought of doing.
Send the user ID with every request. Also embed the user ID into the token. In the server, before any method is accessed, check whether the user id in request and token are the same.
FYI I am using Firebase authentication and tokens, then use AWS API Gateway to authenticate the access to the API. The user Id I was referring to is in database.
How do you think I can overcome this issue and secure the API?

As long as you make sure to pass the tokens only over secured connections, interception of that token is not very likely. If you then use short-lived tokens (such as Firebase's ID tokens), even when a token does get intercepted it can only be used for a short amount of time.
If a token does get intercepted, you can revoke the token, as shown in the Firebase documentation on managing user sessions.
And finally, you can consider implementing App Check for an additional layer of protection, and check that token too in your own backend.

Related

AWS Cognito: Why do you need an ID Token? [duplicate]

Just reading the docs, they seem very similar to me so I can't really discern why to use one over the other. Although identity token seems better since it has custom attributes on it from the user pool (eg: custom:blah and the default ones like name and email).
Right now, I am working with an app that passes the access token back down to the browser so it can use it for making ajax REST calls (there is an auth filter that expects this access token and validates it). Could I just switch out the access token with the id token? The current validation logic is to just get the sub field (the uuid) from the access token, but this sub field is also present in the identity token (as well as practically every other attribute except the aud which I don't need). I just want to make sure I am understanding this right as it is confusing to me why both tokens exist and seem so similar.
The id_token is for your application to process, so you can get all the personal details for your user, like their name, age, email address etc. Generally speaking you shouldn't send this token anywhere else as it contains sensitive user data.
The access_token is used to call other 'external' services (and by external I include other AWS services - these are often called over http). It provides service access authorisation for your user without having to include their personal details.
On the face of it this appears slightly confusing as you can actually use the id_token to access services in the same way as the access_token. However, good practise is to use the access_token in this circumstance and if backend services need user data, they should look it up themselves in Cognito.
EDIT: If you need to authenticate an api call based on claims in the identity token, there are circumstances when this is perfectly valid. But be aware of what details are in the identity token, and whether those claims are suitable to send to the particular API. If you don't need to use any claims from the id_token, use the access_token as this reduces the amount of potentially sensitive data you are sending.
The thing that wasn't obvious from documentation for me about the difference:
If you are using pretoken trigger function and want to add additional information to the claims with claimsToAddOrOverride , you need to use an id token because this information doesn't exist in the access token.
For ex:
event.response = {
claimsOverrideDetails: {
claimsToAddOrOverride: {
'userProfileID': id,
}
},
}
I've expected it in the AppSync resolver with lambda function as source
Speaking about AWS User Pool tokens:
Identity token is used to authenticate users to your resource servers or server applications. For example, if you use Cognito as authorizer in AWS API Gateway you need to use Identity token to call API.
The purpose of the access token is to authorize API operations in the context of the user in the user pool. For example, you can use the access token to grant your user access to add, change, or delete user attributes.
The header for the access token has the same structure as the ID token. However, the key ID (kid) is different because different keys are used to sign ID tokens and access tokens.

How to implement OAuth when the resource and auth servers are same

I have a Django Rest API with JWT authentication which is the backend for a Angular frontend. There are many clients who use the service with our frontend. Now some enterprise clients wanted to integrate the APIs from their system's backend. I don't want to remove JWT from current APIs. I am planning to create new APIs in the same backend with OAuth token for those users.
I wonder what is the best way to implement OAuth for this scenario.
I am thinking Client Credentials grant type is the best way.
Question1: Am I right that client credentials is the right approach ?
For those enterprise users, it is sufficient they get just access token through the UI interface so that they can access all our APIs.
But here the problem is one additional step of getting the Client ID and Client Secret first and using that to get Access Token.
Question 2: What is the use of client ID and client secret ?
Question3: Should my backend hide the process of generating Client ID and Client secret and just give Access token (or) give them Client ID and Client Secret and ask then to generate access token ?
Question 4: If I am giving them Access Token without client id and secret, is that fine to have infinite expiry time? and
TLDR; How to implement OAuth when the resource server and auth servers are same ?
There are 4 grant types in oAuth2 which is meant for different scenarios.
client credential : the consumer (app) make calls to back-end using the bearer token created using apikey(or clientId) and secret only. Mostly used for anonymous calls where generic information is retrieved.
Resource owner password credential (ROPC) : the consumer (app) make calls using the bearer token created using apikey, secret, username and password. Mostly used when you(your authorization server) already know the users(user database is handled in your own system).
Authorization code : the consumer (app) make calls using the bearer token created using an authorization code. The authorization code is provided by a 3rd party (which actually has/manages the logged in user data) and the created authorization code linked to the logged in user. Google and Facebook log in for various sites is a typical example. Facebook/Google gives an authorization code for those websites and they exchange that code for a token.
Implicit grant : Mix of password credential and authorization code. Instead of authorization code, you get a bearer token from the 3rd party authorization server.
Question1: Am I right that client credentials is the right approach ?
I think you can use CC if there is no user level logics in your backend. If userlevel involved, may be ROPC is a better choice
Question 2: What is the use of client ID and client secret ?
Client ID and Client Secret is very similar to username and password in an application level, which is used to obtain bearer token.
Question3: Should my backend hide the process of generating Client ID and Client secret and just give Access token (or) give them Client ID and Client Secret and ask then to generate access token ?
If you are implementing oAuth2, your consumer should create the access token. But looking at your use case, may be even a simple hash of userId+timestamp is sufficient. ;)
Question1: Am I right that client credentials is the right approach ?
Yes. Providing the new APIs do not need to be called in the context of an end user.
Question 2: What is the use of client ID and client secret ?
The client ID allows the auth server to identify the application
requesting the token (it's often carried through to the access token
too, allowing the API to identify the calling application).
The client Secret means the auth server can trust that the client is
genuinely who he says he is as only he should have the private client
secret for his public client ID.
It's effectively a username and password in this scenario.
Question3: Should my backend hide the process of generating Client ID
and Client secret and just give Access token (or) give them Client ID
and Client Secret and ask then to generate access token ?
Your Auth server should issue the client credentials to the application once and the application should provide those credentials every time they wish to obtain a token via the client credentials grant type.
authorization code grant, or implicit grant might be more suitable for this scenario. The first one allows you to add an authentication step before the tokens are returned to the users (might be useful if you want to integrate your JWT authentication to this as well) and the second one is mainly used for single-page applications, and does not include an intermediate authentication step. This one would be useful if you want to improve efficiency.
client_id and client_secret are given to you when you register a client application in your identity provider(authorization server). This client application does not mean an application or an API belonging to your clients, but your own application to which you plan to incorporate OAuth(and OIDC). These two parameters are useful when making the requests to authorization in order to obtain tokens. The server uses those values to determine whether the request is made by a valid application. Only you have access to those values as you will be the one who's registering the application with the server.
I think this question is answered in the previous section.
I think it would be better if you go through this before doing any implementation. It provides most of the basic knowledge you should have before implementing an OAuth system. I hope this answer was useful to you.

Handling the oauth token in a website/service

I have created a website which allows the user to authenticate against oauth2 (from another provider), the basic flow is (assuming a new user):
The user loads my webpage
An OAuth request token key and secret is provided by the OAuth endpoint
I store the request token into the user's cookies
The user is redirected to the OAuth authentication page from an external provider
The user accepts and is redirected by to my webpage with URL parameters which specify the OAuth verifier and OAuth token
Using the request token (retrieved from cookies) and OAuth verifier (passed via URL parameters), I am able to get an access token key and secret from the OAuth endpoint.
I am now able to authenticate with the providers API and use that to get the logged in user ID.
I then store into a MySQL database, the user ID, a token which I generate as a random unsigned integer, OAuth token and OAuth secret. In cases of the token I generate already being in the database, I just continue in a loop until a unique token is generated. The MySQL database has a strong name, username and password. The database user can only access the table in question and only has privileges to add an entry, delete an entry and make a query.
I clear the request token from the user's cookies and instead store the user ID and my generated token.
When a user comes back to my website, I check if they have the user ID and token stored in their cookies, if so I attempt to look up the OAuth token and secret from MySQL. If they are found, I test they are still valid (does the API endpoint accept them) and if so, the user remains 'logged in' to my website. In cases where the user ID or token isn't found in MySQL or cases where it is found, but is not accepted by the endpoint (expired?), I just go back through the flow above.
The above all works correctly, new users can successfully authenticate, returning users find the website remembers them. I do not expose the OAuth token key or secret to the user and instead, give the user this token ID which I generate.
Are there any problems with what I am doing?
Should I be encrypting the OAuth token key and secret in my database?
Is there a problem with the fact if someone was to gain access to the token I generate, along with the user ID, they would be able to call my scripts. Is this a problem?
Should I be encrypting the user ID and token I generate before storing it in the user's cookies? Taking into account, ultimately whatever is stored in the user's cookies will get passed to my script, so if I were to encrypt, store to cookies, then next time read from cookies and decrypt, the user would still be able to access my endpoints by simply passing the encrypted version (assuming the server decrypts, if the client decrypts then the decryption key would be accessible via the users browser anyway), which doesn't immediately appear to offer any further security.
My goal is to tighten up the steps above so it is deemed robust and secure. The actual use case for my web site means it'll only have a tiny number of users (if any) using it. It was more of a learning process for me, combined with implementing something I actually need. But for the learning aspect alone, I would like to make everything sensible and secure. I am not trying to be overly pedantic and implement steps no other similar websites would implement, basically I would like my site to be secure enough that if there ever was a problem, no one could point a finger at me and say I didn't implement an adequate security system.

Django - Temporarily save request token for OAuth 1.0a flow

The Twitter OAuth 1.0a flow requires authenticated request token to be exchanged with access token at consumer or client side after user has authenticated.
The problem that I'm facing is that generating access token needs authenticated request token, request token secret and verifier but the response from the oauth/authentication api doesn't have request token secret. So how do I temporarily save request token secret from oauth/request_token api call so that I can use it in oauth/access_token api call.
I found some solutions from my explorations like Running a Cache server (Memcached, Redis) or using django session feature. But they all seem to be overkill for this task.
I hope to find a simpler solution.
I'm sure you long ago figured this out, but just for future goolers: I decided to a go a more low tech route and create an OAuth token class which includes fields for the fetched and access token. Basically I take the fetched token, store it, then recall it when accessing (as it's in a different view) and then save the access token. Once (if) that's successful than I delete the fetched token.
There's likely a more glamorous way to do this, but if you're clever with your naming convention you can easily keep them straight (i.e. add a CharField for provider and just save the fetched token as twitter_fetched, and the access token as just twitter).
This has the added benefit of allowing you to create an OAuth1 or OAuth1Session from the stored access token.

Facebook Graph API - complete server side auth and API calls

I have an application, that runs on server. On that server is background task, that will post status update on few social networks (Facebook, Twitter, G+). It must be completely server-side.
In Twitter API I'm able to use OAuth header to authorize API request. OAuth HTTP header uses consumer key, consumer secret, access token and access token secret to create the header. With this I'm able to post/update/delete tweets with no user interaction.
How can I do this for Facebook? I found a solution to obtain a long-lived access_token (2 months), but we don't want to regenerate access_token every 60 days. We want to use it for manage our Facebook page - post status updates, but completely server-side.
Am I able to do this for Facebook? Thanks for answers.
PS: I searched stackoverflow hundred-times but with no solution for my problem.
Thanks.
It is not possible for User Access Tokens (they can only be extended to 60 days and need to be refreshed by the user after that), but for posting to a Page you should use a Page Token anyway. An Extended Page Token is valid forever.
Here are some Links to help you get that Extended Page Token:
https://developers.facebook.com/docs/facebook-login/access-tokens/
http://www.devils-heaven.com/facebook-access-tokens/
http://www.devils-heaven.com/extended-page-access-tokens-curl/
A Page Token will post "as Page" btw, but that´s probably what you want. And auto-posting on user profiles is not really allowed anyway, every message has to be 100% user generated and every posting should get authorized by the user.
Pay attention to Access Tokens Expiration & Extentions.
The Page Access Token could be a good solution to only server side calls for testing and data analysis purposes.
Take your User Access Token from Graph API Tool
Extend your User Access Token
Call https://graph.facebook.com/v2.11/me/accounts with your user access token extended
*all calls are GET and this procedure does not use APP Access Token.