Broken Access Control

Types

Type	Example
IDOR	/users/123 → change to /users/456
Privilege Escalation	Normal user accessing admin
Missing function level	API endpoint with no auth check

Prevention

@GetMapping("/orders/{id}")
public ResponseEntity<Order> getOrder(
        @PathVariable Long id,
        Authentication auth) {
    Order order = orderService.findById(id);
    // Check ownership!
    if (!order.getCustomerId().equals(auth.getName())) {
        throw new AccessDeniedException("Not your order");
    }
    return ResponseEntity.ok(order);
}

Key Principles

1. Follow SOLID principles
2. Write clean, readable code
3. Test thoroughly
4. Document decisions
5. Monitor in production

Implementation

• Start simple, refactor as needed
• Use established patterns
• Consider trade-offs
• Review with peers

Continuous Improvement

• Learn from incidents
• Update documentation
• Share knowledge
• Mentor others

Key Points

• Understanding Broken Access Control is essential for production systems
• Always consider scalability and maintainability
• Test thoroughly before deploying to production
• Monitor performance and set up alerting

Common Patterns

1. Validation: Always validate input at the boundary
2. Error Handling: Use structured error responses
3. Logging: Log key events for debugging
4. Testing: Unit, integration, and load tests
5. Documentation: Keep docs updated with code changes