In a regular web app, when someone logs into the system they simply save an encrypted cookie that gets send on each request and the backend decrypts the cookie and uses the e.g. user_id/guid to lookup the user.
How do things differ when authenticating with a angular app?
Is there anything else to consider or it is basically the same process?
We use more or less the same mechanism.
Access to the application as a whole requires authentication - that is unless you're logged in, you don't get any of the javascript experience at all. This could make the login / login failure much less wizzy for the user, but in our authentication provider it's fine.
Part of our auth mechanism means the list of roles that the user has is a data object available within the browser. The javascript code uses this to decide which buttons / menus etc. are displayed. I checked with our security guy and he said something like "Well, it's a kind of direct object reference issue, but as long as each action is authorised properly, you're probably ok." So it's possible that a user could hack data values and change what they can see, but because of the next bit, they can't break our data (or see stuff that they shouldn't).
Each service call our javascript makes is authenticated and authorised. That is, the javascript call will fail if the auth token is missing or bad, but also, we internally match the auth token with a user and a set of permissions, and only execute that if the user is authorised to do so. (Note that this is good practice whether you're using Angular or not). Also note that this applies to GETs as well as POSTs - we don't want to give them data they should not see.
It gets much trickier if your API is hosted separately from your Angular site.
Related
Background
I am looking at the OAuth 2.0 Implicit Grant flow where a user is redirected to an authentication service and a JWT token is sent back a Single Page Application(SPA). The token is stored in a cookie or in local storage and, in the examples i have seen, the application will hide/show certain pages based on whether it can find the token in storage.
Issue
The problem is that in all the examples (official from service providers), i was able to manually add any random but properly formed token to the browser's local storage and got access to the 'secured' pages.
It was explained to me that you cannot validate the token in the SPA because that would require exposing the client secret and that you should validate the token on the API server. This means that you can 'hide' the pages but it is really easy to see them if someone wants to. Having said that you are unlikely to cause any real damage because any data retrieval or actions would need to go through the API server and the token should be validated there.
This is not really a vulnerability but the documentation and examples I have seen do not explicitly cover this nuance and i think that it could lead naive programmers (like myself) to think that some pages are completely secure when it is not strictly the case.
Question
It would be really appreciated if, someone who is better informed than i am, confirm that this is indeed how SPA authentication supposed to work?
I am far from an expert, but I have played a bit in this space. My impression is that you are correct, any showing/hiding of functionality based solely on the presence of a token is easily spoofed. Your SPA could, of course, get into verifying an access token.
But that may just make it a little more challenging to spoof. If someone wants to fake the client into thinking it has a valid token, they can likely manipulate the client-side JS to do that. Unfortunately that's the nature of client-side JS. Much of the code can be manipulated in the browser.
Thus far this is speaking to protecting the user from seeing a UI/UX. Most applications are only beneficial when they have data to populate their UI. That's where the API access token strategy is still sound. The server will verify the token and not give the client any data without it.
So while it's unfortunate that JS can be easily spoofed and manipulated to show things the developer would rather not make visible, this isn't typically a deal-breaker. If you have some awesome UI feature that doesn't need data, and you need to secure access to that UI itself, this model may not be the greatest.
I'm building an admin page for an application and have a state value 'authenticated' that flips from 'false' to 'true' after a successful login (which is authenticated on the server) which then shows the actual admin panel.
Are component state values safe from tampering by the client? Basically, if the client can modify my 'authenticated' state value to 'true', they can skip the login and go straight to the admin panel (which I obviously don't want).
I read that React Dev Tools allows the client to modify values yet everyone says "validate on the server" but I am validating on the server and updating my state accordingly, if the user is approved. If it is not wise to have a state value manage this, what is the right way to conditionally show the admin page after a successful, server-side authenticated login?
I think this is an important question since tampering with state values in a React app can have huge negative consequences on data integrity within an app/database.
TL;DR: Either require an authentication token with every request or require authentication through a session.
Never trust users always. One potentially big issue is if you "hide" admin actions behind the admins page without requiring authentication.
For example, assume the backend server uses a REST API to accept commands. In the admin panel you get links to administrative actions like a button 'Delete Everything' that sends a DELETE request to server.net:8080/api/admin/everything without requiring any authentication. If you're a user, you can find that in the code potentially and then send a DELETE request to that address from anywhere without any repercussions.
We'd never give administrative privileges to anyone who would want to delete everything... Because we'll never untrust someone. Right?
Worse, someone might find the server and fuzz some inputs to it, and oops! They manage to delete everything (or even worse, GET everything stored in the database). This wouldn't be hard to do, especially if the server you use to authenticate is the same server you use to issue commands. History has proven "security through obscurity" to be a very bad paradigm. Every action should be authenticated, even if it seems like the actions will be hard to find.
Generally, providing a JSON web token or some other form of authentication token and having the user send that with every request is a good start at least, especially if it has an expiration date. The token would be provided through a separate request with valid credentials.
Sending a token with every single request obviously isn't ideal. There are a couple of other things to try. For servers using PHP, you can probably trust sessions (though very many people who know more than me would probably disagree). In more modern cases, you could try to use Web Sockets, requiring the token after connection. Then only after authentication with the token do you allow the user to make administrative requests.
That way, even if a user knows the exact command they can send to perform any action, the server won't let them without a current session or token. Unfortunately, unless you're already using Web Sockets or depending on a session, it will likely require a lot of changes. I'd consider this to be critical though.
It is always possible to tamper values in the front-end, there is no way you can rely solely on the front end to ensure security.
Your best approach is to implement some form of authentication and authorization on your backend. In this way, even is some users pretend to be admin, they will be blocked when you do the next request to the server.
Perhaps if you can send more information regarding your problem, we can think of a more specific solution.
I am developing a REST API based on Node / Express and a frontend for it based on React / Redux. Users can login (which gives them access to additional functionality) but they can use basic functionality also without logging in.
When a user logs in, the client makes an HTTP call with the credentials, the server creates a session and returns a user object (user_id and some other data) as well as a session cookie. The React app saves the user object in its Redux state. In subsequent HTTP calls, the user is authenticated through the cookie.
When rendering the user interface, the React app determines whether it is logged in or not by checking for a user object in its state. This is used to grey out some buttons which are only available to logged in users, or to hide the login link when the user is already logged in.
The problem
It could occur that the session expires, or that the user logs out in a different browser tab. The React app has no way of knowing this and thinks it is still logged in (i.e. app state mismatches reality), leading to wrong UI display.
What pattern to solve this?
Put a hook on all Ajax calls to check for 401 and update the
state?
Return session state in HTTP headers (and then?)
A Comet pattern for the server to notify the client that it has been logged out? (not a REST API anymore then)
Additional calls before actual API calls to make sure user is still logged in? (seems wasteful)
And how to deal with this once the client detects it is no longer logged in during an ongoing operation? I'd prefer to handle this in one place rather than all functions making API calls...
I'd be thankful for some best practice!
There are two straightforward ways to deal with this issue in a React application that I can think of. Both inspired by a colleague of mine few days ago.
Use SSE (server-side-events) technology to PUSH notifications. As you correctly pointed out, this makes your API less pure. This approach should be quite an acceptable sacrifice where flawless UX is required AND/OR your server might need to push other notifications to the app.
Establish a short term timer somewhere in your client app (e.g.: setTimeout(...)) that makes periodic calls to a "ping" API endpoint that will return current user/session information. This approach will impact UX for the duration of timeout, often negligible, and is commonly known as polling.
Hope this helps!
As an alternative to the naive polling, you can make it a little smarter by adding an endpoint that lets you know in how many seconds timeout is set to occur for the session at that point in time.
Then ping just before that time (instead of at a certain poll-rate) and update accordingly.
Logging out in another tab would return with an invalid token so would be picked up, too, but not as quickly if this is your main concern.
For this you could use broadcasting to let the other tabs know immediately (or use sessionStorage's change event to simulate a broadcast on unsupported browsers).
Otherwise the best way would be to implement a ServiceWorker; these can handle all requests for your app to the server. It's a centralised piece of code separate from your app that can broadcast to all tabs that a session is lost the moment it sees that one of its requests was rejected, and you can efficiently naively poll from this one place (instead of in each individual tab's runtime).
Since I am using token from the API Server that is valid for a specific period of time. So in addition to setting token in session storage I was thinking of setting up another session storage variable that stores the timestamp at which the token was generated. Then, in my js code I plan to add the validity period (say, 3600 seconds) and check if the token is still valid or not. If it is valid then the user session is valid else it is invalid.
I have an angularjs app that is on a separate domain than my backend, and the users from my backend all have roles and permissions that allow them access to various areas and elements of my frontend.
Before, I was just storing to a cookie and checking as I needed through the use of angular services and whatnot, cool.
Now the permissions datum have reached the point where they are too big to store in a cookie in the browser. And I'm avoiding Localstorage for fear of user tampering.
The Question:
How do I store the users sensitive data (or anything sensitive, really) that are too big for cookies on the client side in a manner that is safe and doesn't require API calls all the time to get?
I don't want to have to phone home every page change to get this data direct from the server when I need it, because I feel this would be really detrimental to the speed and flow of the site, not to mention the frequency at which this would need to happen would be ridiculous for my app.
Keep in mind that I do proper permission checking on the backend before carrying out any actions, but I'm more concerned about users tampering with their permissions to show certain elements that were removed on the frontside before.
What would be your solution or your advice on this?
If it ends up on the user's computer, regardless of whether it's in a cookie, in local storage, in the URL, in the browser's cache, or anywhere else on the user's computer, assume that the user can see it and mess with it. (You could encrypt it, but if your client-side logic knows how to decrypt it, you're back to step one.)
The best that you can do is exactly what you've described - be sure that the server only carries out authorized actions, and never trusts what the user tells it.
I am creating an Angular application, and I am having trouble wrapping my head around the proper way to ensure my application and its users is secure.
I've been reading around many stack discussions, but I believe I am missing some core understanding of what is happening, please correct any errors you see written below.
So far I have a Sinatra server with many (currently mostly hypothetical) resource routes. A user can create an account using an email address and password that is stored in a database after being hashed with BCrypt. When a user logs in, the record is retrieved from the database by email and the password checked for authentication. It is from this point I am not sure how to proceed.
Prior to this I have simply set a session variable and had the server check that the variable exists in order to correctly route logged in users. Now my application is (currently) a single HTML page that uses Angular and ui-router to display different content, so most of the requests are simply returning JSON content.
It is my understanding that Restful applications should generally not use sessions, or rather that the server should respond identically to identical requests and not have its own data that shapes a response. But if I do not store something in a session variable, how could the server know that the client making the request has the correct permissions? And are sessions not stored in the browser anyway, thus not part of the server?
I believe from what I have read, it is possible to create a token which is essentially a large random string, return that string to the client and also store it in a database with a timestamp. The client then provides this token when making requests and the server hits the database to verify it exists and valid. But would the client not also have to store that string in a cookie? I suppose the angular application could store the token in a variable, which would persist while using the ui-router but not if the users navigates using the address bar.
I also do not understand how Basic Auth may or may not fit into this picture. Any help would be greatly appreciated, as well as a pointer to some good resources where I may find a better understanding of these concepts in general.
You want to read up on JWT. There are JWT libraries for Ruby and Angular.
I know you aren't using Node for your backend but a very easy way to see all the pieces working together is to run the angular-fullstack Yeoman generator. It uses JWT and the code is easy to follow.
As far as I can see, whatever you are doing with your sessions can work just fine.
This can be a sample JSON response from the server in case the user is not loged in :
{
"errorCode": 1,
"error": "User not logged in",
"data": {}
}
You can set your own error codes and handle what you want to do. You will send any data only if the user is logged in. For all the pages which don't require authentication, you can set data to whatever you want.
On the angularJS side, you can handle based on error codes, you can redirect the user to the login page and so forth.
The alternate way to support the same on multiple platforms is to use token based approach. The token based approach in simple words work this way.
The user logs in for the first time with his / her credentials.
The server verifies these information and creates a token from which the server is able to decode the user id.
Whenever the client makes the requests, it passes its token with every request.
As the server can decode the user information from the token, it sends or doesn't send the data based on whether that's a right token or not.
The token depends on a secret value. It can be same for all the users or differnet for each based on how you want to implement.
This is all done and you can look at
http://jwt.io/
As #andy-gaskell mentioned, you can look at
http://angular-tips.com/blog/2014/05/json-web-tokens-introduction/
I'm very bad at explaining. Please let me know if any of this doesn't make sense.
you are missing the point of the REST concept. One of the main concepts in the REST apis is that the server should be stateless - this means that you should not store sessions or other "state" in your web server. Every HTTP request happens in complete isolation. Every request should include all data needed by the server to fulfill the request.
But if I do not store something in a session variable, how could the
server know that the client making the request has the correct
permissions?
You can store request scoped variables. This means that they should be only active during the same request. You can store the current logged in user in the request scoped variable. In that way you can get the current user in your invocation of the business method. I'm not familiar with Sinatra but here is the doc: http://www.sinatrarb.com/intro.html#Request/Instance%20Scope
But would the client not also have to store that string in a cookie?
of course you should store your access token in the client side
https://stormpath.com/blog/where-to-store-your-jwts-cookies-vs-html5-web-storage/
as #Andy Gaskell suggest take a look at JWT and fullstack application code generators and forget about the basic auth because it's really "basic".
more useful links:
If REST applications are supposed to be stateless, how do you manage sessions?
http://www.sitepoint.com/php-authorization-jwt-json-web-tokens/