Authentication mechanism absence or evasion - Response tampering - Typescript

Need

Implementation of a secure and reliable authentication mechanism

Context

1. Usage of TypeScript for statically typed JavaScript development
2. Usage of Express for building web applications and handling HTTP requests

Description

Insecure Code Example

import express from 'express';

const app = express();

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

  // Perform authentication logic here

  if (authenticated) {
    res.json({ success: true, message: 'Login successful' });
  } else {
    res.json({ success: false, message: 'Invalid username or password' });
  }
});

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

  // Perform OTP validation here

  if (otpValidated) {
    res.json({ success: true, message: 'OTP validation successful' });
  } else {
    res.json({ success: false, message: 'Invalid OTP' });
  }
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

The vulnerability in this code is related to the absence of proper authentication and validation mechanisms. In the `/login` route, the code checks if the user is authenticated based on the provided username and password. If the authentication is successful, it sends a JSON response with a `success` property set to `true` and a message indicating a successful login. However, there is no proper authentication logic implemented in the code, so anyone can bypass the authentication check by directly sending a request to this route. In the `/unblock` route, the code expects an OTP (One-Time Password) to be provided in the request body. It then performs an OTP validation check. If the OTP is validated, it sends a JSON response with a `success` property set to `true` and a message indicating a successful OTP validation. However, the code does not implement any proper OTP validation logic, making it vulnerable to response tampering. An attacker can exploit this vulnerability by modifying the response of the `/login` request to include a success message, bypassing the authentication check. They can then proceed to send a request to the `/unblock` route without a valid OTP and still receive a response indicating a successful OTP validation. To fix this vulnerability, proper authentication logic should be implemented in the `/login` route, such as checking the provided username and password against a database or using a secure authentication mechanism. Additionally, the `/unblock` route should perform a secure OTP validation process, such as verifying the OTP against a trusted source or using a secure OTP validation mechanism.

Steps

1. Implement a proper authentication mechanism for the '/login' route to ensure that only valid credentials can log in.
2. Move the OTP validation logic to a separate function or middleware to ensure reusability and consistency.
3. Perform the OTP validation before allowing access to any resource that requires OTP verification.
4. Return an appropriate response based on the OTP validation result, such as returning a 401 Unauthorized status code for invalid OTP.
5. Consider implementing additional security measures, such as rate limiting or IP blocking, to prevent brute force attacks on the OTP validation endpoint.
6. Regularly review and update the authentication and OTP validation mechanisms to address any new vulnerabilities or security risks.

Secure Code Example

import express from 'express';

const app = express();

// Middleware for authentication
const authenticate = (req, res, next) => {
  const { username, password } = req.body;

  // Perform authentication logic here

  if (authenticated) {
    next();
  } else {
    res.status(401).json({ success: false, message: 'Invalid username or password' });
  }
};

// Middleware for OTP validation
const validateOTP = (req, res, next) => {
  const { otp } = req.body;

  // Perform OTP validation here

  if (otpValidated) {
    next();
  } else {
    res.status(401).json({ success: false, message: 'Invalid OTP' });
  }
};

app.post('/login', authenticate, (req, res) => {
  res.json({ success: true, message: 'Login successful' });
});

app.post('/unblock', validateOTP, (req, res) => {
  res.json({ success: true, message: 'OTP validation successful' });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

The fixed code addresses the vulnerability by implementing an authentication process and performing the necessary validations on the server-side. The code uses the Express framework to create an HTTP server. It defines two middleware functions: `authenticate` and `validateOTP`. These middleware functions are responsible for handling the authentication and OTP validation processes, respectively. In the `authenticate` middleware, the code extracts the `username` and `password` from the request body. It then performs the authentication logic, which is not shown in the code snippet. If the authentication is successful, the middleware calls the `next()` function to proceed to the next middleware or route handler. Otherwise, it sends a 401 Unauthorized response with an error message. Similarly, in the `validateOTP` middleware, the code extracts the `otp` from the request body. It performs the OTP validation logic, which is also not shown in the code snippet. If the OTP is valid, the middleware calls the `next()` function. Otherwise, it sends a 401 Unauthorized response with an error message. The code defines two routes: `/login` and `/unblock`. The `/login` route is protected by the `authenticate` middleware, ensuring that only authenticated users can access it. If the authentication is successful, it sends a JSON response indicating a successful login. The `/unblock` route is protected by the `validateOTP` middleware, ensuring that only requests with a valid OTP can access it. If the OTP validation is successful, it sends a JSON response indicating a successful OTP validation. The server listens on port 3000, and a console log message is printed to indicate that the server is running. By implementing these authentication and validation processes on the server-side, the fixed code ensures that the OTP validation cannot be bypassed by modifying the response of the request.

References

Last updated

2023/09/18