I have the requirement that only certain user roles should be allowed to log in. The set of roles may change at runtime.
UsernamePasswordToken token = new UsernamePasswordToken(username, password);
subject.login(token);
Which implementation is the most appropriate / secure?
Lookup the user roles (outside of Shiro) before calling subject.login() and raise an AuthenticationException if no role is permitted.
Let the authenticationQuery of the JdbcRealm only return a password (via SQL JOIN), when a user has one of the permitted roles.
Log the user in, then check roles / permissions, and immediately logout and raise AuthenticationException if not permitted.
other options?
You may want to consider user behavior here. If your webapp makes it look like a user was unable to logout, (IMHO) the first thing the user will do is try again, the second thing is they will call the help desk and try to reset their password.
This depends on your actual application, (so take this with a grain of salt). I'd suggest letting the user login and then blocking access e.g. show a 403 page with a ("You shall not pass" warning), or show a 404 (this is what GitHub does as it does NOT leak information that a valid page exists).
This also simplifies the Shiro implementation, just require a role/permission for your routes.
Related
We have one realm with many users and multiple OIDC clients configured. We would like to connect another application (OIDC Client) to the realm. Unfortunately, the client cannot check for any attributes or roles to be present.
How can I configure Keycloak to authenticate with a specific OIDC-client but return failing authentication if users have not a specific role?
Generally this type of option will not work, since authorization redirects occur before you know who the user is, and therefore before you know which roles are involved.
WHAT I WOULD DO
Make an authorization redirect perform only the following job:
Signing in the user and returning the user id (sub claim), along with perhaps a couple of scopes
Then manage roles within your app - the second app should call a Web API that does this:
Get claims from the access token, and also from other sources, then use them for identification and authorization
If a user authenticates but is not entitled to use a particular app, detect this via an API call, then present an Access Denied page in the app after login.
To reach this you should implement the AuthenticatorFactory and Authenticator interfaces of Keycloak. Look here for more infos.
In the authenticate() method you will write something similar to this:
If(client == yourClient){
// Check for roles
}
Otherwise, expected behaviour in case of failure.
Here is how my application should work:
Users can use some functionalities of my application if they have enough chips (token) which they can buy from another application, or they can be granted to them upon some event, whatever.
Users have an attribute associated with them called 'chip', which represents some number. This information should be represented as a claim, probably.
I want Keycloak to do this authorization for me - to check whether user can use the functionality or not. I've come across JavaScript-based policies. It's seems they are able to operate on informations in tokens - like user email etc, but this is not my case where token can contain obsolete information, i.e. when token was generated user had enough chips but since then he spent them.
Maybe token should be refreshed upon spending chips, but in that case, would it be updated with current informations bound to user? Or maybe authorization service can somehow access database during evaluation of a policy? Could this work or are there any elegant solutions to this use case?
Keycloak is not here to check if the user has enough money. Keycloak is here to say if the user is authenticated and if he has the roles for a certain application (admin, user...).
Checking if the user has enough money should be on server-side. For an incoming request, you have to check in the database if the user has enough chips to access the application and if he hasn't you return 403.
I have read the issues about impersonation, and from what i could find so far it can be achieved. I'm not sure tho if the following could be done using it.
A user doesn't have permission to do a certain operation, but it can be done if a supervisor grant him access.
The grant would be only for that operation/request.
is this something that can be done using impersonation, or there is a better approach for this?
Thanks in advance.
Quick brain dump of what you could do: You would have to implement this yourself in the user service in IdentityServer. One approach is to pass a custom param in the acr_values from the client with the ID of the user you want to impersonate (you will also have to pass prompt=login to force the request to go to the login workflow and thus the user service). In your user service implementation in PreAuthenticate you can check if the user is already authenticated, the custom acr_values is present, and the user is allowed to impersonate the user being requested. You'd then assign the AuthenticateResult on the context with the identity of the new user. This short circuits the login process and will return back to the authorization endpoint, and then back to your client app.
I want to make a simple REST web app, where the user interact with the objects through links in an email. The links have a token that can be used to authenticate a user without a username and password, like the ones that are usually used to reset a password.
What are the best practices for such a login-less, token-based authentication system?
I am by no means a security expert.. but some of the points which come to mind are -
Lifetime - The token should expire after a set period of time. Indefinite access using the token certainly doesn't make sense.
Replay attacks - The mechanism should prevent replay attacks.. which means the token should be valid for not only a set period of time, but also fixed number of calls.. Ideally exactly 1. If this number is not exactly 1, then it opens another can of worms..
Unless, its a feature :( For example, by design, the user is expected to share link with others, and anyone with the link should be able to access the resource in question.
Authorization - Granularity of the access granted by the token. Is it black and white.. or is the token also associated with a fixed set of rights. For example - token X was issued for Read-Only access, vs token Y was issued, for same resource with R/W access.
Administration - User / Admin should be able to see and verify any currently active and issued tokens, and associated information (permissions granted / affected resource etc), and explicitly revoke them, if necessary.
Secure Communication - You should consider security of the medium through which the url with token will be sent to the user. i.e. in your scenario, do the users receive emails over secure channel (TLS / SSL)? Should the email itself be protected with DRM?
Man in the Middle / Leaks - Similarly, even though you are providing the url in email, and the user is not logging on using user name and password over SSL, the resource should still be accessed using the url with token over SSL. This will prevent any capturing of the tokens from url, by a man in the middle. You would also need to be very careful about when the users browser may use this url in places you didn't expect..
I can vaguely recall reading about a popular site being affected by their urls being used as Refer Url, when displaying ads on their website.. which means, the advertisers site would probably get the url with the token as Refer.
Generation - Choice of algorithm to generate the token - May seem pretty obvious, but the token should be extremely obscure and near impossible to guess or brute force. The tokens should never be reused and the algorithm should avoid collisions.
Server Side Security - The tokens should probably be treated with same security as you would secure users id and password. If your user database gets hacked, hackers should not get the users passwords and other sensitive information.. Similarly, if your user / resource / token database gets hacked, despite the expiration on the tokens, hackers should not be able to access the resources as users for x hours.
Point is, when the tokens are stored on server side, they should themselves be secured / encrypted.
On the same lines.. just like its bad practice to log information like passwords in log file (specially plain text), You'd also have to consider any place these urls may get logged (plain text) on your server.. For example web server logs. If only super admins should have access to user's database, then they should also be the only ones to be able to see these token.. Not your web server admin and not any hackers parsing the log file after the hack.
Auditing - If there will be a need for auditing, you'd need some mechanism in place to prove that while the user didn't log on to the system, they are indeed the ones who performed the action / operation in question. Would you want to track the ip address and other information along with the request which would help such auditing?
Consent - Do your users even consent to the use of such alternate means of authentication and authorization? Should this be an optional / opt in feature?
EDIT: I found a link to the referrer url problem I was recalling. Although it was in context of user information.
I agree to 10 points of Vikas however from security perspective I have to tell you few points that you must be careful.
I will try to keep as simple as possible. And here I simplify the technical stuff to your special case.
Firstly tokens are used to prevent Cross Site Request Forgery attacks (XSRF). Keep that in your mind. If there is a web platfrom without unique tokens on the forms then any attacker can force the user to make malicious requests.
If you simply try to authenticate the user with a token, this is pretty wrong. Because there must be no simple authentication process and you can not rely on token.
Here is how the login system works in official security documentations, im writing as I remember:
Identification: you have to identify the user firstly, that is generally done with username. YOu will know that there is a user exist in your system.
Authentication: Let's say you have already identified that user A want to login. So you mast authenticate the user A with something that you know and user A know. We call it password simply :) You cannot by pass this step with plain text methods. Passwords are generally encrypted in your db and also through all communication with secure certicates, check ssl.
Authorization: okay you made the authentication somehow, the user has a right to get Authorization. Let's say if the admin type user is logged in, he has differen rigts and if the normal user is logged in then she has regular rights.
Session control: finally you have to control the session with a secure way. Here generally in web applciations people use access tokens for all requests to be sure that the authorized user is aware of the request. As a platform owner you are responsible to secure everything until the session ends. If you don't satisfy the users with your security, then probably your platf is not going to survive longer.
Tokens have different lifetime to expire and different access rights.
Now let's look at what facebok like companies do with mobile aplications. For the mobile app they generate a unique access token which is alway alive. One shortcoming here is, if any attacker steal the mobile token generally she can do anything in the account anytime :) Anyway here our point is how they verify the users with those tokens; firstly the token is unique for that device. (Actually not exactly unique or not dependent on hardware, because if you clearly steal the necessary files from the device then you can use it on another phone). So with this unique access token which is generated with users password at their initial login on mobile app, they can login always automatically with that. And this method is a little similar to what you want to do. However pay attention that they don't authenticate the users with links or email code.
Verification is not an authentication, don't forget that. By sending e-mail you can verify the users if the emailed code is unique and valid for only 30 sec or 1 minute. I hope you got the point.
Here I suggest you to check single sign on across multiple domains, which is really interesting.
Single Sign On across multiple domains
Let's say you are logged in to google.com and then you visit the youtube.com Opps the youtube is already logged in? Yea, cool right, but exist for long time. They can authenticate users accross domains which use different cookies with a little and secure trick. You will read on the link.
If your service is not really confidential and if you want to make your users happy with easy login system. Here is two of my solutions which I love :)
1-) Ask users their email address: just directly send 4-6 digit code as e-mail. Ask user the enter/click on that. There will be no password at all, only unique code on each login.
2-) Let's say you need to verify the user with a stronger way than email. Then mobile phone :) Here trick is; you will not send the verification code to user, but they will send what you tell them to you.
Ask to user to send a SMS with a unique CODE to XXXXXX your number :) Connect your mobile operator with your web service and check whether the code is sent to you by the user :)
There is always a trade-off between security and simplicity, and also with complexity. You have to find the balance.
Don't try to make it simple if your security is going away.
Don't try to make it complex if it'll seem more secure.
Hope those informationn help you.
I am building a messaging application using BackboneJS which naturally persists using a REST interface.
The issue I'm having is that I don't know how to restrict what data a user can pull back from the API. For instance a call to /messages would, at the moment, return messages for ALL users. I would like that resource to only return messages belonging to the current user.
Searching online seems to indicate that oAuth2 is the best way to solve this issue but all the tutorials talk about been redirected to another place to confirm access and retrieve an access token.
Given that my users will have already logged into the message application and that the REST API is actually part of the same application I don't like the idea of asking the users to confirm that my own app can access my own API.
Is there a better way?
oAuth2 is probably your best bet -- you definitely don't want to roll your own security. However, the flavor of oAuth2 you are thinking of is probably not what you want.
oAuth2 has four different flavors, known as authorization grant types:
Authorization code: This is the type you are thinking about. It is often called three-legged oAuth, because there are three actors in the token granting process (app, resource owner, and user). The app asks the user whether it is ok for the resource owner to give specific type(s) of access to the resource. It is a rather complex process that allows the validation of user credentials without allowing the app access to them. This is not necessary in your case, since you are both the app and resource owner.
Client credentials: This is a method for authorizing a client application with the server. It does not use user credentials at all. If you completely trust your client application (all client applications) to correctly protect user data and not expose other user's data to the user using the app, or you are providing only non-user data via the API (for example, map data or catalog data), you might be able to use this fairly simple type of oAuth2. However, if you want to be vigilant in protecting user data (and not allow apps to get to the data without the user providing credentials), you might not use this one.
Resource owner password credentials: The username and password of the user is passed via https to your backend server, which authenticates and authorizes access by providing an access token. The access token can then be passed with each call, and it remains valid for accessing the backend until a configurable time period has elapsed. This means that someone intercepting the token could only use it successfully for a limited amount of time (some number of minutes, generally). The interceptor would not know the username and password of the user. In addition, you can supply the app with a refresh token, which can be used to get a new access token once it has expired (until the refresh token expires -- usually with a significantly longer expiration date). Since the credentials are not passed across the wire often (and must only be passed encrypted), this is often the best solution for protecting user credentials and not requiring the user to pass them in often (good user experience). Implementation is much simpler than for the authorization code grant type.
Implicit: This is the least secure method -- no credentials are validated server side at all. This is usually used for client side scripting languages where credentials cannot be stored safely. If you are worried about security at all, avoid this type if possible.
So, check out OAuth 2.0, and look for the resource owner password credentials grant type.