NoSQL.md

Authentication NoSQL Injection

The code below is vulnureable to NoSQL Injection

const MongoClient = require('mongodb').MongoClient;

// Connect to the MongoDB database
MongoClient.connect('mongodb://localhost:27017/test', (err, db) => {
  if (err) {
    // Handle the error
  } else {
    // Use the user-provided value as a parameter in the find() method
    db.collection('users').find({
      username: req.body.username
    }).toArray((err, result) => {
      if (err) {
        // Handle the error
      } else {
        // Do something with the result
        console.log(result);
      }
    });
  }
});

Why it's vulnerable?

This code uses the MongoDB Node.js driver to connect to a MongoDB database and search for a user with a given username. However, if the user supplies a malicious value for the username parameter, they can modify the search query to return arbitrary data from the database.

Impact?

For example, if the user supplies the following value for the username parameter:

username: {$gt: ''}

The find() method will construct the following query:

{
  username: {$gt: ''}
}

This query will match all documents in the users collection, allowing the attacker to retrieve sensitive information from the database.

How to fix?

To prevent this type of attack, it's important to properly validate and sanitize user-provided input before using it in a NoSQL query. In this case, you could use a regular expression to ensure that the username parameter only contains allowed characters, such as letters, numbers, and underscores:

const MongoClient = require('mongodb').MongoClient;

MongoClient.connect('mongodb://localhost:27017/test', (err, db) => {
  if (err) {
    // Handle the error
  } else {
    // Validate the username using a regular expression
    const usernameRegex = /^[a-zA-Z0-9_]+$/;
    if (!usernameRegex.test(req.body.username)) {
      // The username is invalid, return an error
      return res.status(400).send('Invalid username');
    }

    // Use the user-provided value as a parameter in the find() method
    db.collection('users').find({
      username: req.body.username
    }).toArray((err, result) => {
      if (err) {
        // Handle the error
      } else {
        // Do something with the result
        console.log(result);
      }
    });
  }
});

This code uses a regular expression to validate the username parameter before using it in the find() method. If the username contains any characters that are not allowed by the regular expression, the request will be rejected with a bad request error. This will prevent NoSQL injection attacks by ensuring that the username parameter can't be used to construct a malicious query.