Mongo NoSQL Injection Attack and How to Prevent Them /with NodeJs-Express Code Examples

Mongodb, NodeJs, Express

NoSQL injection attacks are becoming more common as the use of NoSQL databases like MongoDB increases. In this tutorial, we’ll discuss what NoSQL injection attacks are, how they work, and how to prevent them.

1. What is a NoSQL Injection Attack?

A NoSQL injection attack occurs when an attacker exploits vulnerabilities in your code or database to inject malicious code. In the case of MongoDB, this can happen when user input is not properly validated or sanitized before being used in a query. The attacker can then manipulate the query to access, modify or delete data from your database.

1. How Does a NoSQL Injection Attack Work?

A NoSQL injection attack works by exploiting vulnerabilities in your application’s code or database. The attacker will typically use input fields on your website to enter malicious code. This code will then be used in a query to your database. If the code is not properly sanitized or validated, the attacker can manipulate the query to access or modify data they should not have access to.

1. How to Prevent NoSQL Injection Attacks

Preventing NoSQL injection attacks requires proper input validation and sanitization. Here are some best practices to follow:

• Use parameterized queries instead of building queries with user input.
• Validate and sanitize all user input before using it in a query.
• Use a whitelist approach to validation, only allowing specific types of input.
• Limit user privileges so they can only access the data they need.
• Use encryption to protect sensitive data.
• Keep your database and software up-to-date with the latest security patches.

To prevent NoSQL injection attacks, it is important to properly validate and sanitize user input before using it in database queries.

Using Express Mongo Sanitize

Express Mongo Sanitize is a package that provides middleware to sanitize user input before it is used in a database query. It is designed specifically to prevent NoSQL injection attacks in Node.js applications that use MongoDB.

To use Express Mongo Sanitize in your application, you first need to install it using npm:

npm install express-mongo-sanitize

Next, you need to require the package in your code and use it as middleware in your Express application:

const express = require('express');
const mongoSanitize = require('express-mongo-sanitize');
const app = express();
// Sanitize user input 
app.use(mongoSanitize());

With this middleware in place, any user input that is sent in the request body or query parameters will be automatically sanitized before being used in a MongoDB query.

Example Usage and What if you don’t care example

Let’s say you have a route in your application that retrieves a user’s information from the MongoDB database using their email address. Without proper input validation and sanitization, an attacker could insert a malicious payload into the email parameter and potentially gain unauthorized access to sensitive data.

To prevent this type of attack, you can use Express Mongo Sanitize to sanitize the email parameter before using it in the database query:

const express = require('express');
const mongoSanitize = require('express-mongo-sanitize');
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/myapp');
// Sanitize user input
app.use(mongoSanitize());
// Retrieve user information
app.get('/user', async (req, res) => {
  try {
    const user = await User.find({ email: req.query.email });
    res.json(user);
  } catch (err) {
    console.error(err);
    res.status(500).send('Server Error');
  }
});

With Express Mongo Sanitize in place, any malicious payload inserted into the email parameter will be automatically sanitized, preventing the NoSQL injection attack.

What would happen if it wasn’t sanitized?
Anyone reaching this route could send a query like:

// client sends query like this: domain.com/api/users?email[$ne]=x
// some parsers...
console.log(req.query.email) // output -> { $ne: 'x'}
const user = await User.find({ email: req.query.email }); // boom! 
//it will fetch all users whose email is not "x"

If the query sends mongo’s operators in this way and we somehow parse it and perform the query, a user would be able to access all the user data in our system.

Conclusion

In this article, we have discussed how to prevent NoSQL injection attacks in your Node.js application using the Express Mongo Sanitize package. By properly validating and sanitizing user input, you can protect your application from potential security vulnerabilities. Remember to always sanitize user input before using it in a database query to ensure the security of your application.

Hüseyin Isik — Software Developer

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