Insecure object reference - Corporate information

Need

Secure access control and data validation for employee information

Context

• Usage of TypeScript for statically typed JavaScript development
• Usage of Express for building web applications and APIs
• Usage of body-parser for parsing request bodies in Express

Description

Non compliant code

import express from 'express';
import bodyParser from 'body-parser';

const app = express();
app.use(bodyParser.json());

interface Employee {
  payrollNumber: string;
  name: string;
  email: string;
}

let employees: Employee[] = [];

app.post('/upload', (req, res) => {
  const uploadedEmployees: Employee[] = req.body.employees;

  // Insecure object reference vulnerability
  employees = uploadedEmployees;

  res.status(200).json({ message: 'Employee information uploaded successfully' });
});

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

The vulnerability in this code is an insecure object reference.

In the app.post('/upload') route handler, the code receives a request with an array of employees in the request body. It then assigns this array directly to the employees variable, effectively overwriting the existing employee data.

This poses a security risk because there is no validation or authorization check to ensure that the user making the request has the necessary permissions to modify the employee data. An attacker could exploit this vulnerability by sending a request with a modified array of employees, including employees from a third-party company to which they do not have access.

By simply uploading an Excel file and changing the payrollNumber, an attacker can associate new employees or update the information of existing employees in a third-party company's employee database.

To mitigate this vulnerability, the code should include proper authorization checks to ensure that only authorized users with the necessary permissions can modify the employee data.

Steps

• Implement authentication and authorization to ensure that only authorized users can access and modify employee information.
• Instead of directly assigning the uploaded employees to the 'employees' variable, validate and sanitize the data before storing it.
• Use a unique identifier for each employee instead of relying on the 'payrollNumber' as the identifier.
• Implement access controls to ensure that users can only modify employee information within their own company.
• Consider encrypting sensitive employee information to protect it from unauthorized access.

Compliant code

import express from 'express';
import bodyParser from 'body-parser';

const app = express();
app.use(bodyParser.json());

interface Employee {
  id: string;
  payrollNumber: string;
  name: string;
  email: string;
  companyId: string;
}

let employees: Employee[] = [];

// Authentication and Authorization middleware
const authenticateUser = (req, res, next) => {
  // Implement authentication logic here
  // Check if the user is authenticated and has necessary permissions
  // If not, return an error response
  // Otherwise, proceed to the next middleware
  next();
};

// Validate and sanitize employee data middleware
const validateEmployeeData = (req, res, next) => {
  // Implement data validation and sanitization logic here
  // Check if the uploaded employee data is valid and sanitize it if necessary
  // If the data is invalid, return an error response
  // Otherwise, proceed to the next middleware
  next();
};

// Access control middleware
const checkAccessControl = (req, res, next) => {
  // Implement access control logic here
  // Check if the user has permission to modify employee information for the specified company
  // If not, return an error response
  // Otherwise, proceed to the next middleware
  next();
};

app.post('/upload', authenticateUser, validateEmployeeData, checkAccessControl, (req, res) => {
  const uploadedEmployees: Employee[] = req.body.employees;

  employees = uploadedEmployees;

  res.status(200).json({ message: 'Employee information uploaded successfully' });
});

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

The fixed code addresses the vulnerability by implementing several middleware functions to ensure authentication, data validation, and access control.

1. The code imports the necessary modules, including Express and body-parser, to handle HTTP requests and parse JSON data.

2. The code defines an interface called "Employee" that specifies the structure of an employee object. This helps ensure type safety and consistency when working with employee data.

3. The code initializes an empty array called "employees" to store the uploaded employee information.

4. The code defines three middleware functions:

   a. "authenticateUser" middleware: This function is responsible for authenticating the user. It should be implemented to check if the user is authenticated and has the necessary permissions. If not, it should return an error response. If the user is authenticated, it calls the next middleware.

   b. "validateEmployeeData" middleware: This function is responsible for validating and sanitizing the uploaded employee data. It should be implemented to check if the data is valid and sanitize it if necessary. If the data is invalid, it should return an error response. If the data is valid, it calls the next middleware.

   c. "checkAccessControl" middleware: This function is responsible for enforcing access control. It should be implemented to check if the user has permission to modify employee information for the specified company. If not, it should return an error response. If the user has permission, it calls the next middleware.

5. The code defines a POST route '/upload' that handles the file upload process. It specifies the middleware functions to be executed in the order of authentication, data validation, and access control. If all the middleware functions pass, the uploaded employee data is stored in the "employees" array. Finally, it sends a success response.

6. The code starts the Express server and listens on port 3000.

By implementing these middleware functions, the fixed code ensures that only authenticated users with the necessary permissions can upload and modify employee information. It also validates and sanitizes the uploaded data to prevent any potential security vulnerabilities.

References

• 287.Insecure object reference - Corporate information