Reolicate csrf download file vulnerability

You already know the csurf library. The cookie - parser library allows your application to parse cookies sent by the browser. Then, change the content of the server. Here, you include the modules just installed and configure them as middleware in the Express HTTP pipeline.

In particular, you are configuring the csurf middleware to use cookies instead of the server session object. As you did for the session-based approach, you will access the CSRF token through the req. This way, you fix the CSRF vulnerability with an approach quite similar to the previous case.

The strategies discussed in the previous section were based on checking the validity of a request. You can use a strategy based on accepting requests from specific origins, typically the same domain that hosts the web application.

Let's take a look at this approach. To make sure that an HTTP request is coming from a legitimate client, you should validate its origin. It means that the server should determine the source origin of the request and compare it with the target origin. You can rely on these headers because they cannot be altered programmatically , that is, only the browser can set them. Let's take a look at how you can implement this technique. Again, start with the original vulnerable project by setting up the working environment.

You added a middleware that grabs the Origin and Referer headers and compares their values with the Host header's value. It takes into account that the Referer header may be missing at the first request to the server. Also, it takes into account that old browsers don't support the Origin header. If one of those headers matches the Host header, you can process the request. Otherwise, an error is raised. Do not consider this a production-ready code. It is just for demonstration purposes.

Many issues may affect the correct behavior of origin validation. An alternative way to invalidate requests coming from unauthorized origins is using the sameSite cookie property. This property has been recently introduced, so old browsers may not support it. To learn how you can adopt this approach, restore the original project as described in the Set up the environment section. Then, open the server. You assigned the 'strict' value to the sameSite property of the session cookie.

This value instructs the browser not to send the session cookie when the request comes from a different domain. In other words, that cookie must be sent to the server only by pages loaded from the same website. Now, you may want to verify that the attacker's website is no longer able to perform any unintentional change on the movie streaming website.

Unfortunately, if you try to perform the usual attacker steps as before, you will be able to carry out the attack. This is because you are using the same domain name localhost for both the vulnerable and the attacker websites, and cookies are shared independently of the port. So, to correctly test the behavior of the sameSite property, you need to differentiate the domain names. This time everything should go as expected.

However, unlike the other scenarios, your redirection from the attacker's website to the user's profile page doesn't get an error. You simply get the vulnerable website's home page as an unauthenticated user. In fact, this time, the browser is not sending the session cookie to the streaming movie website since the request comes from another site.

Here are a few that we recommend you avoid. Remember that all cookies, even the secret ones, will be submitted with every request. All authentication tokens will be submitted regardless of whether or not the end-user was tricked into submitting the request.

Furthermore, session identifiers are simply used by the application container to associate the request with a specific session object. The session identifier does not verify that the end-user intended to submit the request. Applications can be developed to only accept POST requests for the execution of business logic. The misconception is that since the attacker cannot construct a malicious link, a CSRF attack cannot be executed. Unfortunately, this logic is incorrect.

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Stack Overflow works best with JavaScript enabled. In the " Proxy " tab, right click on the raw request to bring up the context menu. In the Proxy "Intercept" tab, ensure "Intercept is off". If the attack has been successful and the account information has been successfully changed, this serves as an initial check to verify whether the attack is plausible.

Now login to the application using a different account in this example the admin account for the application. For the attack to fire in a real world environment, the victim needs to access a page under the attacker's control while authenticated. In our example web application, a new password can be set for the account using the email address. In this way an attacker could gain full ownership of the account. Visit the web application you are testing in your browser.