Prevent MVC Application from Cross Site Request Forgery Attacks
All web application platforms are potentially vulnerable to CSRF (Cross-Site Request Forgery) attacks. The best way to prevent this attack in MVC application is to use Anti-Forgery token.
Consider a banking website "www.bank.com" contains an action method DeleteUser in User Controller. When a web request comes from a client, the controller fetches the user id from session and deletes the user from database. Consider one hacker created a site "www.songs.com" and it contain one button 'Latest songs'. The button click event calls the "www.bank.com/User/DeleteAccount". A user is logged in "www.bank.com" and he is visiting "www.songs.com" using the same browser with another tab. When he clicking the 'Latest songs' button, his account will delete from the bank database. To avoid these type of unwanted requests from other sites, MVC application developers use Anti-Forgery Token.
Anti-Forgery Token is mainly used in form POST actions to verify the source of the POST data. In this method, for each page request, the web server sends a cookie to the client browser. While posting the data or next request time, the web server uses this cookie for client authentication. If the request is coming from an unauthorized site, the cookie will be null or invalid. By adding [ValidateAntiForgeryToken] above the controller and @Html.AntiForgeryToken() in the view page, we can prevent cross site requests forgery.
Using the Code
The below code illustrates how Anti-Forgery Token Cross Site Request Forgery:
Without Anti-Forgery Token
1. Controller (Controller for deleting the user account)
public class UserController : Controller { public ActionResult DeleteUser() { var userId = (int)Session["userId"]; DeleteUserFromDb(userId);//Function for deleting the user from Database return View(); } }
2. View (Button for deleting the user account in Bank page)
[ValidateAntiForgeryToken] public class UserController : Controller { public ActionResult DeleteUser() { var userId = (int)Session["userId"]; DeleteUserFromDb(userId);//Function for deleting the user from Database return View(); } }
Santosh Kumar Singh
23-May-2016Prevent MVC Application from Cross Site Request Forgery Attacks
All web application platforms are potentially vulnerable to CSRF (Cross-Site Request Forgery) attacks. The best way to prevent this attack in MVC application is to use Anti-Forgery token.
Consider a banking website "www.bank.com" contains an action method DeleteUser in User Controller. When a web request comes from a client, the controller fetches the user id from session and deletes the user from database. Consider one hacker created a site "www.songs.com" and it contain one button 'Latest songs'. The button click event calls the "www.bank.com/User/DeleteAccount". A user is logged in "www.bank.com" and he is visiting "www.songs.com" using the same browser with another tab. When he clicking the 'Latest songs' button, his account will delete from the bank database. To avoid these type of unwanted requests from other sites, MVC application developers use Anti-Forgery Token.
Anti-Forgery Token is mainly used in form POST actions to verify the source of the POST data. In this method, for each page request, the web server sends a cookie to the client browser. While posting the data or next request time, the web server uses this cookie for client authentication. If the request is coming from an unauthorized site, the cookie will be null or invalid. By adding [ValidateAntiForgeryToken] above the controller and @Html.AntiForgeryToken() in the view page, we can prevent cross site requests forgery.
Using the Code
The below code illustrates how Anti-Forgery Token Cross Site Request Forgery:
Without Anti-Forgery Token
1. Controller (Controller for deleting the user account)
2. View (Button for deleting the user account in Bank page)
With Anti-Forgery Token
1. Controller
2. View
Cross Site Request Error
Server Error in '/' Application.
The required anti-forgery cookie "__RequestVerificationToken" is not present.
Description: An unhandled exception occurred during the execution of the current web request.
Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Web.Mvc.HttpAntiForgeryException:
The required anti-forgery cookie "__RequestVerificationToken" is not present.
Anupam Mishra
04-May-2016