Securing ExpressJS with CSRF protection using signed double submit cookies

ExpressJS is a popular web application framework for Node.js that is commonly used to build APIs and web applications. Like any web application framework, ExpressJS is vulnerable to different security threats, such as Cross-Site Request Forgery (CSRF) attacks. In this tutorial, we will focus on implementing CSRF protection using double submit cookie in ExpressJS.

CSRF attacks occur when a malicious website tricks a user’s browser into making an unauthorized request to a different website. This can lead to a variety of security issues, such as changing a user’s password, making unauthorized transactions, and more. By implementing CSRF protection in ExpressJS, you can prevent these attacks and protect your application and users.

There are various ways to implement CSRF protection in ExpressJS, and one common method is using double submit cookie. This method involves creating two separate cookies – one cookie with a random token value that is sent in a request header, and another cookie with the same token value that is sent in a request body. When a request is sent to the server, the server can compare the token values in the request header and body to verify the authenticity of the request.

To implement CSRF protection using double submit cookie in ExpressJS, follow these steps:

1. Install the necessary packages:
   First, you need to install the cookie-parser and csurf packages in your ExpressJS project. These packages will help you manage cookies and implement CSRF protection.

To install the packages, run the following command in your terminal:

npm install cookie-parser csurf

1. Set up the middleware:
   Next, you need to set up the cookie-parser and csurf middleware in your ExpressJS application. Add the following code to your app.js or main server file:

const express = require('express');
const cookieParser = require('cookie-parser');
const csrf = require('csurf');

const app = express();

app.use(cookieParser());
app.use(csrf({ cookie: true }));

1. Generate and send CSRF tokens:
   When rendering your HTML templates, you need to generate and send CSRF tokens to your front-end. Add the following code to your route handlers that render HTML templates:

app.get('/login', (req, res) => {
  const csrfToken = req.csrfToken();
  res.render('login', { csrfToken });
});

In your HTML template, you can include the CSRF token as a hidden input field:

<form action="/login" method="post">
  <input type="hidden" name="_csrf" value="{{csrfToken}}">
  <!-- Other form fields -->
</form>

1. Validate CSRF tokens:
   Finally, you need to validate CSRF tokens in your route handlers that handle POST requests. Add the following code to your POST route handlers:

app.post('/login', (req, res) => {
  const { _csrf } = req.body;

  if (req.csrfToken() !== _csrf) {
    res.status(403).send('Invalid CSRF token');
    return;
  }

  // Process login request
});

With these steps, you have implemented CSRF protection using double submit cookie in ExpressJS. By following these best practices, you can protect your application from CSRF attacks and ensure the security of your users’ data.

It’s important to keep in mind that CSRF protection is just one aspect of web application security. It’s recommended to use other security measures, such as input validation, authentication, and authorization, to build a robust and secure application.