Broken Authorization

Broken authorization, also known as broken access control, occurs when an application fails to properly enforce restrictions on what authenticated users are allowed to access or modify. This vulnerability allows attackers to bypass authorization mechanisms and gain unauthorized access to sensitive data or functionality. Below, I'll explain broken authorization in detail and provide examples of scenarios where it can occur.

Understanding Broken Authorization:

Broken authorization occurs when an application lacks proper checks to enforce access controls. This can result from various issues such as insufficient validation of user permissions, inadequate enforcement of role-based access controls (RBAC), or flaws in session management.

Example Scenarios of Broken Authorization:

1. Insufficient Validation of User Permissions: In this scenario, an application might allow users to access sensitive functionality or data without adequately verifying their permissions. For example, a forum website might fail to check if a user has the necessary privileges to delete posts, allowing any authenticated user to delete content.

2. Inadequate Enforcement of Role-Based Access Controls (RBAC): Role-based access controls define what actions users with different roles are permitted to perform. Broken authorization can occur if an application fails to properly enforce these roles. For instance, a banking application might allow a regular user to access administrative features if the corresponding controls are not properly enforced.

3. Flaws in Session Management: Session management vulnerabilities can also lead to broken authorization. For example, if an application does not invalidate sessions after a user logs out or if session tokens are not sufficiently random or unpredictable, attackers may be able to hijack sessions and gain unauthorized access to other users' accounts.

Vulnerable Code Example:

Consider the following PHP code snippet that demonstrates broken authorization:

<?php
// admin_panel.php

session_start();

// Check if user is logged in
if (!isset($_SESSION['user'])) {
    header('Location: login.php');
    exit;
}

// Check if user is an administrator
if ($_SESSION['user']['role'] !== 'admin') {
    echo "Access denied. You do not have permission to access this page.";
    exit;
}

// Display admin functionality
echo "Welcome, ".$_SESSION['user']['username'].". You have administrator privileges.";

// Display admin panel...
?>

Explanation of Vulnerability:

In the above code example, the application checks if the user is logged in and then verifies if the user has an administrator role. However, if an attacker manipulates the session data or bypasses the authentication mechanism, they may be able to access the administrative functionality without proper authorization checks.

Mitigation Strategies:

To prevent broken authorization vulnerabilities, developers should implement the following best practices:

1. Enforce Proper Access Controls: Ensure that access controls are properly enforced at both the function and data levels throughout the application.

2. Implement Role-Based Access Controls (RBAC): Use RBAC to define roles and permissions for different user groups and restrict access to sensitive functionality accordingly.

3. Apply Principle of Least Privilege: Grant users only the permissions necessary to perform their intended tasks and restrict access to sensitive resources or functionality whenever possible.

4. Regular Security Reviews: Conduct regular security reviews and code audits to identify and address access control vulnerabilities proactively.