A cross-site request forgery (CSRF) attack occurs when a trusted user of a web application can be forced, by an attacker, to perform sensitive
actions that he didn’t intend, such as updating his profile or sending a message, more generally anything that can change the state of the
application.
The attacker can trick the user/victim to click on a link, corresponding to the privileged action, or to visit a malicious web site that embeds a
hidden web request and as web browsers automatically include cookies, the actions can be authenticated and sensitive.
Ask Yourself Whether
- The web application uses cookies to authenticate users.
- There exist sensitive operations in the web application that can be performed when the user is authenticated.
- The state / resources of the web application can be modified by doing HTTP POST or HTTP DELETE requests for example.
There is a risk if you answered yes to any of those questions.
Recommended Secure Coding Practices
- Protection against CSRF attacks is strongly recommended:
- to be activated by default for all unsafe HTTP
methods.
- implemented, for example, with an unguessable CSRF token
- Of course all sensitive operations should not be performed with safe HTTP methods like
GET which are designed to be
used only for information retrieval.
Sensitive Code Example
public void ConfigureServices(IServiceCollection services)
{
// ...
services.AddControllersWithViews(options => options.Filters.Add(new IgnoreAntiforgeryTokenAttribute())); // Sensitive
// ...
}
[HttpPost, IgnoreAntiforgeryToken] // Sensitive
public IActionResult ChangeEmail(ChangeEmailModel model) => View("~/Views/...");
Compliant Solution
public void ConfigureServices(IServiceCollection services)
{
// ...
services.AddControllersWithViews(options => options.Filters.Add(new AutoValidateAntiforgeryTokenAttribute()));
// or
services.AddControllersWithViews(options => options.Filters.Add(new ValidateAntiForgeryTokenAttribute()));
// ...
}
[HttpPost]
[AutoValidateAntiforgeryToken]
public IActionResult ChangeEmail(ChangeEmailModel model) => View("~/Views/...");
See
