My website is full SPA, and all of the authenticated user's requests are done using access token, the only form that unauthenticated users have access to is login form. So is csrf protection necessary? What potential security issues could I face if I disable csrf protection from my website? Thanks.
If I understand your setup, it is as follows:
User POSTs credentials (eg: login form)
Server returns auth token in response
User includes token in a request header with every subsequent request
If this is accurate, and assuming that you're using TLS and properly validating tokens, I think you are already well protected against Cross-Site-Request-Forgeries.
The typical CSRF protection is to send a token that only the legitimate website can see (eg, by setting a cookie), and then expecting that same token to be returned either in follow-up request headers, query parameters (not a good idea), or request body. Token-based authentication such as yours already meets these requirements.
In short, if an evil site is able to circumvent your setup to forge requests (CSRF), then the evil site could probably use the same vulnerability to defeat a typical CSRF protection.
For non-PHP based web-clients (JSON) making use of Laravel Controllers; What would be the potential alternatives to CSRF tokens in Laravel to secure web requests?
If your API uses an authentication scheme that does not depend on the authentication token being sent automatically by the browser (which practically means the token or session id is not in a cookie), your API is not vulnerable to CSRF. This includes token-based auths, unless the token is stored in a cookie.
If cookies are used to pass auth tokens (including session ids, which is the same in this respect), you need CSRF protection for all requests that change server state (mostly data, but also logon status or privilege level for example).
For Laravel, you need to pass the token value from the XSRF-TOKEN cookie as a request header value in X-CSRF-TOKEN. With jQuery, this is easily accomplished in any client framework by reading the cookie value and adding it to requests:
$.ajaxSetup({
headers: {
'X-CSRF-TOKEN': csrfCookieValue
}
});
If your client is not browser based, you can implement a different protection than the one in Laravel already. OWASP has a cheat sheet on what your options are, probably double submit is the easiest to implement while being reasonably secure. In very short, you create a random token and send that to the server as a cookie and also as a request header, the server only compares whether the two (cookie and header) match. This works, because an attacker on a differnet origin (domain) cannot set or access a cookie for the application origin due to the same origin policy in browsers.
I think the whole point on using a csrf token is for use inside the app. If you are sending your request via ajax from the app itself then you can simply append the csrf_token to the request. However, if you are sending data from an external source via json then the best way would be to use oAuth to secure access to your api. Luckily laravel has already built this functionality with laravel/passport so implememting it is fairly straightforward.
I'm exploring JWT and OAuth2 for a Javascript Single-Page-App which will make calls to a backend server-side API. I've come up with a security process that involves using two tokens and gives me the advantage of avoiding the need to have an additional server-side session storage:
The first time the client JS app is loaded up, user sends username/password over SSL to OAuth2 server. The server will set a cookie (normal cookie that is readable by client, without any HttpOnly flag set) that contains a JWT with an OAuth2 access token inside it's claims (along with some other non-confidential data in the JWT claims, ie. user's first/last name, country, role/permission). The server will also set a HttpOnly cookie that will contain the OAuth2 refresh token.
The cookies set by the server will be included on every request from the client automatically (always over SSL), so the server will receive the JWT (see step 3) and both confirm the signature and confirm the OAuth2 access token. The server will also confirm the refresh token. Since the server is checking the access token and refresh token against the OAuth2 database on each request, this gives us the ability to revoke access (which we would not be able to do with the JWT signature alone). We can do a "hard" revoke which revokes both access and refresh token. And we can do a "soft" revoke which just revokes the access token (for instances where perhaps some data that we keep in the JWT claim gets updated, ie. user changes their name or country or role). A soft revoke would be invisible to the client end user (it wouldn't disrupt their logged in status).
In step 2 above, the server will actually look for the JWT in a specific header set by the client (instead of the cookie set by the server). For example, the client JS app will read the JWT from the cookie and then set the JWT in another part of the header. By requring the client to explicitly set a header key/value containing the JWT shows that the client was able to read it's own cookie, thus preventing against XSRF (cross-site request forgery).
The HttpOnly cookie that contains the refresh token ensures we are protected against XSS (ie. some malicious javascript that sneaked its way onto our client). If our JWT was stolen, access still wouldn't be granted because the refresh token was not also seen or stolen by the JS.
With this approach we get all these benefits:
We don't need a server-side session storage. Since we are hitting an OAuth2 server then we can simply just include some extra data in the JWT that we return (non-confidential data). We wouldn't need to re-query/refresh the data in the JWT every time, but perhaps only when the OAuth token is revoked (ie. was revoked when some user data was changed that we include in the JWT's). No need to tackle the storage/scaling requirement that comes with using sessions. The client JS app can use this data like any other app would normally use sessions. For instance I can display a user's name on every "page" in the app. We could also just use websockets, but the JWT is a good backup place for adding some data if we need it.
We are protected against XSRF.
We are protected against XSS.
We can revoke access and also log users out (which is not easily possible with JWT alone).
SSL prevents man-in-the-middle attacks.
The JWT adds a little extra security hurdle for attackers to pass versus just a normal JSON object serialized in the cookie. The attacker would need to get the server-side key for signing JWT's (in addition to OAuth access). The JWT is also a standard, so easier for a trusted developer to work with.
The JWT can be easily passed down to other micro-services sitting behind the OAuth layer to use service-to-service. We can pass it around as "session like" data access to all the services on a request. If a service want's to change something in that data, then they can inform OAuth2 server and it will "soft" revoke the user's current JWT (not really much different from the process with a session storage) and provide a new one.
I haven't exactly seen anyone detail a security process like this yet. Many I see seem to only talk about using JWT with an OAuth2 access token inside and don't elaborate much more. So my question is, does this approach indeed provide the benefits I listed above? If not, what am I missing here and what security hole have I not covered for?
Good Morning,
I'm developing an app in ionic and there are some $http requests(angular) that send data to a server controller(yii 1) to save data on database. I finished my app, but it doesn't have security. I was wondering how to protect it, because right now anyone if look my $http request can know what parameters have to send, and kill my app.
What I should do to protect it? Maybe through tokens? I'm really lost with security methods.
Thank you so much,
Carles.
well When you research web application security you will come across Cross-Site Request Forgery (CSRF). This attack vector is taking advantage of cookies, but in a preventable way.
Most attacks focus on stealing your cookies because nearly every website uses cookies as a form of authentication. The setup is this: when a user logs into your server, you set a cookie in the browser. This cookie contains a unique ID which is a link to the user’s session information in your database. The browser supplies this cookie on future requests, and the server knows who you are.
On the surface this sounds not-so-bad, but here is the catch: the web browser can be tricked into making requests to your server, even if the end-user didn’t perform the action themselves.
Using POST Requests
It is sometimes thought that using proper form-based POST requests will mitigate this attack, but that is not true.
Using HTTP-Only or Secure cookies
While you definitely should use these flags on your session cookie, they don’t implicitly stop the attack: the browser still sends the cookies to your domain when a request is made to your domain. Your server does not know if this is a real user or an attack.
How To Prevent CSRF
You can achieve this by relying on a set of rules that browsers respect, called the Same-Origin Policy. This policy asserts that certain sensitive operations are performed by JavaScript code that is running on our website, not some other website.
Angular packages the CSRF token approach, making it simpler for us to implement. For every request that your Angular application makes of your server, the Angular $http service will do these things automatically:
Look for a cookie named XSRF-TOKEN on the current domain.
If that cookie is found, it reads the value and adds it to the request as the X-XSRF-TOKEN header.
Thus the client-side implementation is handled for you, automatically! But this does leave the server side pieces in your hands. You will need to do the following parts:
During login: create the CSRF token (with a random, un-guessable string), and associate it with the user session. You will need to send it on the login response as the XSRF-TOKEN cookie.
Assert that all incoming requests to your API have the X-XSRF-TOKEN header, and that the value of the header is the token that is associated with the user’s session.
That’s it! With a little bit of backend work, you now have a strategy which protects you from CSRF attacks.
you will find a working example of how to prevent CSRF attack here
and for theory of understanding CSRF attacks please follow this reference
I've been reading up on REST and there are a lot of questions on SO about it, as well as on a lot of other sites and blogs. Though I've never seen this specific question asked...for some reason, I can't wrap my mind around this concept...
If I'm building a RESTful API, and I want to secure it, one of the methods I've seen is to use a security token. When I've used other APIs, there's been a token and a shared secret...makes sense. What I don't understand is, requests to a rest service operation are being made through javascript (XHR/Ajax), what is to prevent someone from sniffing that out with something simple like FireBug (or "view source" in the browser) and copying the API key, and then impersonating that person using the key and secret?
We're exposing an API that partners can only use on domains that they have registered with us. Its content is partly public (but preferably only to be shown on the domains we know), but is mostly private to our users. So:
To determine what is shown, our user must be logged in with us, but this is handled separately.
To determine where the data is shown, a public API key is used to limit access to domains we know, and above all to ensure the private user data is not vulnerable to CSRF.
This API key is indeed visible to anyone, we do not authenticate our partner in any other way, and we don't need REFERER. Still, it is secure:
When our get-csrf-token.js?apiKey=abc123 is requested:
Look up the key abc123 in the database and get a list of valid domains for that key.
Look for the CSRF validation cookie. If it does not exist, generate a secure random value and put it in a HTTP-only session cookie. If the cookie did exist, get the existing random value.
Create a CSRF token from the API key and the random value from the cookie, and sign it. (Rather than keeping a list of tokens on the server, we're signing the values. Both values will be readable in the signed token, that's fine.)
Set the response to not be cached, add the cookie, and return a script like:
var apiConfig = apiConfig || {};
if(document.domain === 'example.com'
|| document.domain === 'www.example.com') {
apiConfig.csrfToken = 'API key, random value, signature';
// Invoke a callback if the partner wants us to
if(typeof apiConfig.fnInit !== 'undefined') {
apiConfig.fnInit();
}
} else {
alert('This site is not authorised for this API key.');
}
Notes:
The above does not prevent a server side script from faking a request, but only ensures that the domain matches if requested by a browser.
The same origin policy for JavaScript ensures that a browser cannot use XHR (Ajax) to load and then inspect the JavaScript source. Instead, a regular browser can only load it using <script src="https://our-api.com/get-csrf-token.js?apiKey=abc123"> (or a dynamic equivalent), and will then run the code. Of course, your server should not support Cross-Origin Resource Sharing nor JSONP for the generated JavaScript.
A browser script can change the value of document.domain before loading the above script. But the same origin policy only allows for shortening the domain by removing prefixes, like rewriting subdomain.example.com to just example.com, or myblog.wordpress.com to wordpress.com, or in some browsers even bbc.co.uk to co.uk.
If the JavaScript file is fetched using some server side script then the server will also get the cookie. However, a third party server cannot make a user’s browser associate that cookie to our domain. Hence, a CSRF token and validation cookie that have been fetched using a server side script, can only be used by subsequent server side calls, not in a browser. However, such server side calls will never include the user cookie, and hence can only fetch public data. This is the same data a server side script could scrape from the partner's website directly.
When a user logs in, set some user cookie in whatever way you like. (The user might already have logged in before the JavaScript was requested.)
All subsequent API requests to the server (including GET and JSONP requests) must include the CSRF token, the CSRF validation cookie, and (if logged on) the user cookie. The server can now determine if the request is to be trusted:
The presence of a valid CSRF token ensures the JavaScript was loaded from the expected domain, if loaded by a browser.
The presence of the CSRF token without the validation cookie indicates forgery.
The presence of both the CSRF token and the CSRF validation cookie does not ensure anything: this could either be a forged server side request, or a valid request from a browser. (It could not be a request from a browser made from an unsupported domain.)
The presence of the user cookie ensures the user is logged on, but does not ensure the user is a member of the given partner, nor that the user is viewing the correct website.
The presence of the user cookie without the CSRF validation cookie indicates forgery.
The presence of the user cookie ensures the current request is made through a browser. (Assuming a user would not enter their credentials on an unknown website, and assuming we don’t care about users using their own credentials to make some server side request.) If we also have the CSRF validation cookie, then that CSRF validation cookie was also received using a browser. Next, if we also have a CSRF token with a valid signature, and the random number in the CSRF validation cookie matches the one in that CSRF token, then the JavaScript for that token was also received during that very same earlier request during which the CSRF cookie was set, hence also using a browser. This then also implies the above JavaScript code was executed before the token was set, and that at that time the domain was valid for the given API key.
So: the server can now safely use the API key from the signed token.
If at any point the server does not trust the request, then a 403 Forbidden is returned. The widget can respond to that by showing a warning to the user.
It's not required to sign the CSRF validation cookie, as we're comparing it to the signed CSRF token. Not signing the cookie makes each HTTP request shorter, and the server validation a bit faster.
The generated CSRF token is valid indefinitely, but only in combination with the validation cookie, so effectively until the browser is closed.
We could limit the lifetime of the token's signature. We could delete the CSRF validation cookie when the user logs out, to meet the OWASP recommendation. And to not share the per-user random number between multiple partners, one could add the API key to the cookie name. But even then one cannot easily refresh the CSRF validation cookie when a new token is requested, as users might be browsing the same site in multiple windows, sharing a single cookie (which, when refreshing, would be updated in all windows, after which the JavaScript token in the other windows would no longer match that single cookie).
For those who use OAuth, see also OAuth and Client-Side Widgets, from which I got the JavaScript idea. For server side use of the API, in which we cannot rely on the JavaScript code to limit the domain, we're using secret keys instead of the public API keys.
api secret is not passed explicitly, secret is used to generate a sign of current request, at the server side, the server generate the sign following the same process, if the two sign matches, then the request is authenticated successfully -- so only the sign is passed through the request, not the secret.
This question has an accepted answer but just to clarify, shared secret authentication works like this:
Client has public key, this can be shared with anyone, doesn't
matter, so you can embed it in javascript. This is used to identify the user on the server.
Server has secret key and this secret MUST be protected. Therefore,
shared key authentication requires that you can protect your secret
key. So a public javascript client that connects directly to another
service is not possible because you need a server middleman to
protect the secret.
Server signs request using some algorithm that includes the secret
key (the secret key is sort of like a salt) and preferably a timestamp then sends the request to the service. The timestamp is to prevent "replay" attacks. A signature of a request is only valid for around n seconds. You can check that on the server by getting the timestamp header that should contain the value of the timestamp that was included in the signature. If that timestamp is expired, the request fails.
The service gets the request which contains not only the signature
but also all the fields that were signed in plain text.
The service then signs the request in the same way using the shared
secret key and compares the signatures.
I will try to answer the the question in it's original context. So question is "Is the secret (API) key safe to be placed with in JavaScript.
In my opinion it is very unsafe as it defeats the purpose of authentication between the systems. Since the key will be exposed to the user, user may retrieve information he/she is not authorized to. Because in a typical rest communication authentication is only based on the API Key.
A solution in my opinion is that the JavaScript call essentially pass the request to an internal server component who is responsible from making a rest call. The internal server component let's say a Servlet will read the API key from a secured source such as permission based file system, insert into the HTTP header and make the external rest call.
I hope this helps.
I supose you mean session key not API key. That problem is inherited from the http protocol and known as Session hijacking. The normal "workaround" is, as on any web site, to change to https.
To run the REST service secure you must enable https, and probably client authentification. But after all, this is beyond the REST idea. REST never talks about security.
What you want to do on the server side is generate an expiring session id that is sent back to the client on login or signup.
The client can then use that session id as a shared secret to sign subsequent requests.
The session id is only passed once and this MUST be over SSL.
See example here
Use a nonce and timestamp when signing the request to prevent session hijacking.