csrf-guard

Simple Anti-CSRF Token implementation for Express applications.

This package only uses Node.js native crypto module and no other dependency. I did my best to follow OWASP CSRF token best practices. Now it's your responsibilty to follow best practices for session management. I do recommend you read this article before anything else.

Disclaimer: This package is still under development, I do NOT recommend using it for production yet.

Installation

npm:

npm install csrf-guard

yarn:

yarn add csrf-guard

GitHub:

git clone https://github.com/venomaze/csrf-guard.git

Usage

First register the middleware:

const express = require('express');
const session = require('session');
const CSRFGuard = require('csrf-guard');

const app = express();

// DO NOT USE SESSION LIKE THIS!
app.use(
  session({
    secret: 'secret_key',
  })
);

app.use(
  new CSRFGuard({
    secret: 'secret_key', // Secret key is required
  })
);

Then you have access to two getToken and isTokenValid methods from request object.

1. Generating a token (Remember you have to use csrf_token name for the token):

app.get('/', async (req, res) => {
  const token = await req.getToken();
  const form = `
    <form action="/test" method="POST">
      <input type="hidden" name="csrf_token" value="${token}" />
      <input type="text" name="username" />
      <input type="submit" />
    </form>
  `;

  res.send(form);
});

2. Validating the token:

app.post('/test', (req, res) => {
  const isTokenValid = req.isTokenValid();
  const message = isTokenValid ? 'The token is valid.' : 'Token is NOT valid.';

  res.send(message);
});

Token generation methods

We have to options, the first one is Synchronizer Token Pattern and the second one is HMAC Based Token Pattern. You can read more about them here.

Synchronizer Token Pattern

To be able to use this method, you have to set synchronizer to true in options object. With this method you have access to forced mode which generates a new token even if there is one already. This is the default method.
Setting up:

app.use(
  new CSRFGuard({
    secret: 'secret_key',
    synchronizer: true,
  })
);

Generating token:

const token = await req.getToken(true); // Forced is set to true. This way you'll get a new token per request. (Default to false)

HMAC Based Token Pattern

To be able to use this method, you have to set synchronizer to false in options object. With this method you have access to expiryTime option which gives you this possibility to expire tokens even if the session id isn't changed. By default, tokens won't be expired until the session is regenerated.
Setting up:

app.use(
  new CSRFGuard({
    secret: 'secret_key',
    synchronizer: false,
    expiryTime: 5000, // Tokens will be expired after 5 seconds
  })
);

Generating token:

const token = req.getToken();