Why we need to use #Html.AntiForgeryToken()?
I searched but I didn't get satisfactory answer.
This is a security feature to help protect your application against cross-site request forgery.
Example:
Let's assume you have a register functionality in your web app. You have an AccountController (example.com/account/register) where you expect people to submit their info. Normally before someone posts the registration information needs to visit the actual (example.com/account/register) than submit the form.
Let say I am a bad guy and I want to flood your server with junk info all I need to do is just keep posting directly to (example.com/account/register) without visiting your site. So in order to stop me you implement AntiForgeryToken so you can make it sure I visited the page before I submitted the registration information.
Another example is http://www.binaryintellect.net/articles/20e546b4-3ae9-416b-878e-5b12434fe7a6.aspx.
This is to prevent Cross-site request forgery in your MVC application. This is part of the OWASP Top 10 and it is vital in terms of web security. Using the #Html.AntiforgeryToken() method will generate a token per every request so then no one can forge a form post.
What is the use of #Html.AntiForgeryToken()?
Live - Scenario :
Suppose, you are logged into your bank account and are going to transfer some money to your friend. A hacker knows that you are logged in and also knows the URL of the money transfer submission. Suddenly, you get an email and check it. You see an image and by mistake, you click on that. Then, after a minute or so, you get another message that some amount has been deducted from your account. Actually, that image had been sent by the hacker and behind that image a URL has been submitted on your click.
So that we use AntiForgeryToken() in application prevent from hackers.
Antiforgery() is for stopping robotic fill up of any forms. Which will stop adding data without getting into the form
AntiForgeryToken is a security token generated by the .Net Core web application, which is used to validate a post request to guard against Cross-Site Request.
AntiforgeryToken used for validating the post request. So if we access an MVC or RazorPages view which contains the form element with an attribute 'method="post"' then the view gets rendered with an automatic generated AntiforgertyToken value, which gets injected into the form as hidden input field.
Related
currently i'm working on ASP .NET MVC 4 application. We are using the provided [ValidateAntiForgeryToken] and the corresponding #Html.AntiForgeryToken() to generate the hidden field in our forms which are submitted using POST.
So far the mechanism seems to be working properly because if I don't provided the token as input hidden field to the target Action annotated with [ValidateAntiForgeryToken] an error is raised as expected.
However i found really strange that if i captured several generated token using Firebug or Chrome inspector, copy them into notepad and then go to a different page which also uses the AntiForgeryToken and basically replace the hidden field with any of the previous token generated, an error is not raised. I was expecting to always have a 1:1 relation (Page Hidden Field - ValidationAtServer], since if someone is able to obtain that value, will be able to forge any request to any form in the application which need the AntiForgeryToken
I was under the impression that once a token was generated it should not be possible to reuse the same token over an over, I see this a security flaw in the Framework itself.
If someone can provide more insight will be greatly appreciate it.
AntiForgeryToken is session base, so that each user has the same token but another user will have a different token. This descussion may be usefull for you: AntiForgeryToken changes per request
It's normal behaviour, because it's supposed that antiforgery token isn't compromised. If an atacker was able to compromise token, that means that atacker already has opportunity to compromise any other tokes, that would be generated. E.g. man in middle attacks.
So basically there is no need to gereate Antiforgery token per each request, and it will allow you to use already generated one for Ajax requests on current page.
I have been trying to work out if I can have a login form on my static homepage. I would like to have some static pages and it would be great to have a login form on them. I spent some time getting more familiar with the authenticity_token that is generated with form_tag and although I realize we want to generally check all requests that aren't GET requests I feel like it might be possible to leave it out for a login because we aren't trusting the user with anything until after they are logged in. If a malicious site tried to use CSRF at this point it would need to know the login and password at which point the user is compromised anyway.
I definitely don't want to open up any security holes in my application and I appreciate all that rails does to keep this working, but in this situation am I right to think I can just submit a form without the token?
The purpose of the token is so that data cannot easily enter your system unless it is coming directly from that form. When a user visits the site, they get a cookie that matches the token in the form. When the form is submitted, those tokens must match.
If someone can submit the data from outside the form, you are opening up the potential for a script to make continuous login attempts. It's fairly easy to write something that would automate going to your site, getting a cookie and logging in using the form, but it's definitely more work. Think of it as another layer of security that you can have without negatively affecting your users.
I have an ASP.NET MVC 3 application. The site involves people writing lengthy responses using a textarea in a web form. Occasionally, users are complaining that they are getting redirected to the log in form after they post their data. I am not sure exactly why they are getting logged out because the users do not typically provide enough information on their errors. I believe it is due either to a session time out or the application has been restarted for some reason. This is on a shared web hosting site and it does not have its own app pool.
In any case, regardless of the reason, I would like to capture that post data and save it to a db or text file. How can I get the post data and save it while the controller redirects the user to the login screen.
I know the long term plan would be to identify why the timeout is occurring. But for now I want to be able to grab the post data and recover it at a later time.
First, in order to avoid timeouts, I would recommend using client-side heartbeat solution (like http://plugins.jquery.com/project/Heartbeat)
Second, assuming that you are using forms authentication, in order to save posted data, when Forms Authorization Module is redirecting your users, you will need to intercept redirects in EndRequest HttpApplication event handler in Global.asax or your own module.
The way to intercept those requests is not that straightforward, since on "EndRequest" pipeline step you will see 302 HTTP status code (redirect instruction), not 401 (Unauthorized error). So you may check if request is not authenticated (HttpContext.User.Identity.IsAuthenticated) and request is redirected - in this case you may save what you see in the request.
Otherwise you would need to disable forms authentication and use some solution, which is closer to ASP.NET MVC.
one solution can be to put a javasscript timer which keeps on hitting the server after specified interval to keep session alive until u figure out the cause of session time out (only i its the session timeout problem)
If you want to stop the session from timing out, you can add a hidden iframe on the page. For example, create a new page called KeepSessionAlive and do this:
<meta http-equiv="refresh" content="600">
where content = seconds.
I don't know about MVC 3, but the way you can get and store the post values is to catch them before redirecting the user to the Login page.
I need to create a website with non standard authorizaion logic (or rather not exactly the site. It should be separate Area in existing ASP.NET MVC3 application). Access to most of the pages sould be available only to authorized users. Authorization is carried out on the token passed in the link. After the user arrived to this area, the token should be checked and if it’s valid site will create a session key for 30 minutes (we already have our own mechanisms of session managment and it should be used).
Workflow example :
Third-party website generates a link for user, e.g. https://example.com/securedPage/?accountId=123456&token=XXXXX
Our site check this token (it depends on the page from URL, in this case https://example.com/securedPage/)
If the token is valid, example.com obtains a session key for the user and stores it in cookies.
Then user continues browsing whole website and only session is checked.
I’m new to MVC framework, so I’d like to ask several questions about architecture.
What is an apropriate place for this logic? ActionInvoker, Global.asax etc.?
Currently I'm trying to create my own ActionInvoker and keep this logic there, but I'm afraid that it could be a wrong way.
If I understand correctly you want yo extend the Action of the controller to inject/check your token.
I think the global action filters should help you.
I have an app I'm writing in rails 3 w/ cancan and devise. I'm curious if authorizing post actions on your controllers is necessary or helpful from a security standpoint? Assuming all my controller actions require authentication w/ devise (ie user must be logged in).
I can see why I need authorization through cancan on my controller actions that use GET's since a user can simply input the url they wish to visit freely and this must be locked down. However, with posts the user must post the data from a form, which is protected against an xss attack with a token.
In this case would it be safe to assume that if i limit the visibility of, say, a button in my view with cancan that the user wouldn't be able to submit a form maliciously?
Thanks alot
EDIT:
Thanks for the quick answer guys. As it has been pointed out below a malicious user can forge a form post using tools such as firebug and thus authorization is necessary.
What would be the best way to simulate this type of interaction (a user posting to an url with a form they've hacked) using capybara / cucumber?
Thanks again.
A user can submit a POST request regardless of whether they are on your website or not. You're correct in thinking that the security token will help prevent XSS, but I would add authentication in for other methods of attacks.
A good (free) ebook to read if you're concerned about security is the Ruby on Rails Security Guide. It outlines all common forms of malicious attacks and even explores some of the lesser used (but just as effective) methods. It also gives great solutions on how to make your application more secure.
You should validate a users authorization in the controller.
With simple tools like FireBug, you can edit the content of a form manually and even add more text fields or similar. The XSS protection won't help you with that.
The user would still be able to generate the button (any method from using Firebug to changing browser code would do) on client side and send the form. If I remember correctly tokens are sent in HTML header co it wouldn't be a problem to forge the form.