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Automatic information enumeration - Personal Information

Need​

Prevention of unauthorized access to personal information

Context​

  • Usage of TypeScript for statically typed 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/:id', (req, res) => {
  const userId = req.params.id;
  const userInfo = getUserInfo(userId);
  
  res.json(userInfo);
});

function getUserInfo(userId: string) {
  // Code to fetch user information from the database
  // ...
  return userInfo;
}

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

The vulnerability in the provided code is an automatic information enumeration vulnerability. This vulnerability allows an attacker to list personal information and login methods of platform users without proper authentication or authorization.

In the code, there is an endpoint defined as /users/:id which accepts a user ID as a parameter. When a GET request is made to this endpoint, the code retrieves the user information from the database using the getUserInfo function and returns it as a JSON response.

The problem with this code is that it does not enforce any authentication or authorization checks before returning the user information. This means that any user, without proper authentication, can access the personal information of any other user by simply providing their user ID in the request.

This vulnerability can have serious consequences as it allows an attacker to identify the login methods used by users and obtain strategic information from their accounts. It violates the principle of least privilege and can lead to privacy breaches and unauthorized access to sensitive information.

To mitigate this vulnerability, proper controls should be implemented to limit the information that can be viewed by a user. This can be achieved by implementing authentication mechanisms such as cookies or session tokens to ensure that only authorized users can access their own information. Additionally, authorization checks should be performed to ensure that a user can only access their own information and not that of other users.

Steps​

  • Implement authentication and authorization mechanisms to ensure that only authenticated and authorized users can access user information.
  • Use session tokens or cookies to associate user information with the authenticated user.
  • Modify the '/users/:id' route handler to check if the user is authenticated and authorized to access the requested user information.
  • If the user is not authenticated or authorized, return an appropriate error response instead of returning the user information.
  • Ensure that the user ID parameter is validated and sanitized to prevent any potential injection attacks.
  • Implement access controls to limit the information that can be viewed by a user based on their role or permissions.
  • Regularly update and patch the dependencies used in the application to address any known security vulnerabilities.

Compliant code​

import express from 'express';

const app = express();

// Middleware to authenticate and authorize users
app.use((req, res, next) => {
  // Code to authenticate and authorize the user
  // ...

  // If the user is not authenticated or authorized, return an error response
  if (!authenticated || !authorized) {
    return res.status(401).json({ error: 'Unauthorized' });
  }

  // If the user is authenticated and authorized, proceed to the next middleware
  next();
});

app.get('/users/:id', (req, res) => {
  const userId = req.params.id;
  const userInfo = getUserInfo(userId);
  
  res.json(userInfo);
});

function getUserInfo(userId: string) {
  // Code to fetch user information from the database
  // ...
  return userInfo;
}

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

The fixed code addresses the vulnerability by implementing authentication and authorization controls using middleware in an Express.js application.

First, the code imports the necessary dependencies, including the Express framework.

Then, an instance of the Express application is created.

The code defines a middleware function that is used to authenticate and authorize users. This middleware function is executed for every incoming request before reaching the '/users/:id' route handler.

Inside the middleware function, there should be code to authenticate and authorize the user. This code is not shown in the provided code snippet, but it should check if the user is authenticated and authorized based on the provided credentials or session token.

If the user is not authenticated or authorized, the middleware function returns a 401 Unauthorized response, indicating that the user is not allowed to access the requested resource.

If the user is authenticated and authorized, the middleware function calls the next() function to proceed to the next middleware or the route handler.

The code then defines a route handler for the '/users/:id' endpoint. This endpoint expects a parameter 'id' in the URL, representing the user's ID. Inside the route handler, the code retrieves the user information by calling the getUserInfo() function, passing the user ID as a parameter.

The getUserInfo() function is responsible for fetching the user information from the database. The implementation of this function is not shown in the provided code snippet, but it should include proper database queries to retrieve the user information securely.

Finally, the code starts the Express application and listens on port 3000 for incoming requests.

Overall, the fixed code implements authentication and authorization controls using middleware to ensure that only authenticated and authorized users can access the user information endpoint.

References​

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