Protecting Your Next.js App from Cross-Site Request Forgery (CSRF) Attacks

What is a CSRF Attack?

Imagine you’re logged into your online banking site, and an attacker tricks you into performing an unintended action, such as transferring money to their account. This is a classic example of a CSRF attack. The attacker exploits the fact that your browser has an active session with the banking site, allowing them to make requests on your behalf without your knowledge or consent.

How Do CSRF Attacks Occur?

To understand how CSRF attacks work, let’s consider a scenario where an attacker creates a malicious website that sends a request to your online banking site. If you’re logged into your banking site, the request will be sent with your authentication credentials, allowing the attacker to perform actions on your behalf. This can happen through various means, such as:

• Clicking on a malicious link
• Submitting a form on a malicious website
• Executing JavaScript code on a malicious website

Protecting Your Next.js App from CSRF Attacks

Fortunately, there are several ways to protect your Next.js app from CSRF attacks. Here are some effective strategies:

1. 1. Use SameSite Cookies

SameSite cookies are a type of cookie that can only be sent with requests originating from the same domain. By setting the SameSite attribute to Strict or Lax, you can prevent cookies from being sent with cross-site requests.

const cookieOptions = {
  httpOnly: true,
  sameSite: 'Strict',
};

1. 1. Use HTTP-Only Cookies

HTTP-only cookies are cookies that cannot be accessed by JavaScript code. By setting the HttpOnly flag, you can prevent attackers from stealing your cookies.

const cookieOptions = {
  httpOnly: true,
};

1. 1. Use CSRF Tokens

CSRF tokens are random values generated by the server and included in every request. By verifying the token on each request, you can ensure that the request is legitimate and not a CSRF attack.

const csrfToken = generateCSRFToken();
const cookieOptions = {
  httpOnly: true,
  sameSite: 'Strict',
  value: csrfToken,
};

Implementing CSRF Protection in Next.js

To implement CSRF protection in Next.js, you can use the next-csrf package. Here’s an example of how to use it:

1. Install the next-csrf package: npm install next-csrf
2. Create a setup file for next-csrf: npx next-csrf setup
3. Wrap your API routes with the csrf middleware:

   import csrf from 'next-csrf';
   
   const apiRoute = async (req, res) => {
     await csrf(req, res);
     // Handle API request
   };

By following these steps, you can ensure that your Next.js app is protected against CSRF attacks.