Need

Prevention of automatic information enumeration

Context

• Usage of TypeScript for type-checking and static typing in JavaScript development
• Usage of Express for building web applications and APIs

Description

Non compliant code

        import express from 'express';

const app = express();

app.get('/users', (req, res) => {
  const users = [
    { id: 1, name: 'John Doe', email: 'johndoe@example.com' },
    { id: 2, name: 'Jane Smith', email: 'janesmith@example.com' },
    { id: 3, name: 'Bob Johnson', email: 'bobjohnson@example.com' },
  ];

  res.json(users);
});

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

The vulnerability in this code is that it exposes sensitive user information through an API endpoint without any form of authentication or authorization. The /users endpoint returns a JSON response containing an array of user objects, each containing their id, name, and email.

This can be a security risk as it allows anyone who can access the API endpoint to obtain personal information about the users of the system. An attacker can use automated tools to enumerate this information, potentially gathering a large amount of data about the system's users.

To mitigate this vulnerability, the code should implement proper authentication and authorization mechanisms. Only authorized users should be able to access the /users endpoint, and the sensitive information should be protected from unauthorized access.

Steps

• Remove the '/users' route from the application
• If the '/users' route is necessary, implement authentication and authorization mechanisms to restrict access to the route
• Implement input validation and filtering to prevent the disclosure of sensitive information in the response
• Consider implementing rate limiting to prevent automated enumeration attempts

Compliant code

        import express from 'express';

const app = express();

// Implement authentication and authorization mechanisms here

app.get('/users', (req, res) => {
  // Implement input validation and filtering here

  const users = [
    { id: 1, name: 'John Doe' },
    { id: 2, name: 'Jane Smith' },
    { id: 3, name: 'Bob Johnson' },
  ];

  res.json(users);
});

// Implement rate limiting here

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

The fixed code is written in TypeScript and uses the Express framework to create a server. It addresses the vulnerability by implementing several security measures.

1. Authentication and Authorization: The code mentions that the implementation of authentication and authorization mechanisms should be done before accessing any sensitive information. This ensures that only authorized users can access the data.

2. Input Validation and Filtering: The code suggests implementing input validation and filtering before processing any user input. This helps to prevent any malicious input from being executed and reduces the risk of code injection attacks.

3. Limited Information Exposure: The code defines a route for retrieving user data at the '/users' endpoint. However, it only returns a predefined array of user objects with limited information such as their ID and name. This prevents the exposure of sensitive information.

4. Rate Limiting: The code mentions the need to implement rate limiting. Rate limiting helps to prevent abuse or excessive usage of the server resources by limiting the number of requests a client can make within a specific time frame.

5. Port Configuration: The code does not explicitly mention port configuration, but it listens on port 3000. It is important to configure the server to listen on appropriate ports and ensure that unnecessary ports are closed to reduce the attack surface.

Overall, the fixed code demonstrates a proactive approach to security by implementing authentication, input validation, limited information exposure, rate limiting, and proper port configuration. These measures help to mitigate the risk of automatic information enumeration and enhance the security of the application.

References

• 047. Automatic information enumeration