Designing a Secure Multi-Layer AWS Application Architecture

In production environments, security should be built into every layer of the application architecture. Here's how I designed a comprehensive security architecture for a production application that provides multiple layers of protection leveraging CloudFront. By leveraging CloudFront's global edge network, I was able to achieve sufficient performance improvements for international users without the complexity and cost of multi-region deployment.

Architecture Overview

The architecture implements a defense-in-depth strategy with multiple security layers:

1. AWS WAF - Web application firewall for threat protection
2. CloudFront CDN - Content delivery and DDoS protection
3. Application Load Balancer - Traffic distribution with custom security
4. ECS Services - Containerized application layer
5. Private Database & Cache - Isolated data layer

Security Layers Explained

Layer 1: AWS WAF Protection

AWS WAF sits at the edge, filtering malicious traffic before it reaches the application. It protects against:

• SQL injection attacks
• Cross-site scripting (XSS)
• DDoS attacks
• Bot traffic and scraping attempts

Layer 2: CloudFront CDN

CloudFront provides additional security and performance benefits:

Security Benefits:

• DDoS protection with AWS Shield
• Geographic restrictions
• SSL/TLS termination
• Origin access control

Performance Benefits:

• 30% faster response times for international users compared to direct ALB access
• Greater performance impact for users in remote locations like USA compared to closer regions
• Bandwidth optimization - CloudFront reduces costs as outbound traffic from ALB to CloudFront edge locations is free

Real-World Impact:

• All international users: 30% improvement in response times
• Remote locations (USA, Europe): Even more significant performance gains due to greater distance from origin country, Korea
• Cost efficiency: Free data transfer between ALB and CloudFront, with only end-user delivery charged

Layer 3: Custom Security Headers

A critical security feature prevents direct access to the Application Load Balancer:

Custom Header: X-Security-Example: Secret

• CloudFront adds this header to all requests forwarded to the ALB
• ALB rejects any requests without this specific header
• Prevents direct ALB access, ensuring all traffic goes through the secure pipeline
• Acts as a shared secret between CloudFront and ALB

Layer 4: Network Segmentation

The VPC implements proper subnet isolation:

Public Subnet:

• Application Load Balancer
• ECS Services (API servers)

Private Subnet:

• MySQL Database (Aurora)
• Redis Cache (containerized on EC2)

This ensures database and cache layers are never directly accessible from the internet.

Request Flow

1. Users access the application via HTTPS
2. AWS WAF filters and validates requests
3. CloudFront serves cached content or forwards to ALB
4. CloudFront adds the custom security header
5. ALB validates the security header and load balances to ECS
6. ECS services process requests and interact with database/cache

Key Security Benefits

Prevents Direct Access

The custom header mechanism ensures no one can bypass CloudFront and WAF protections by directly accessing the ALB endpoint.

Defense in Depth

Multiple security layers ensure that if one layer is compromised, others provide continued protection.

Network Isolation

Database and cache components in private subnets are completely isolated from direct internet access.

Centralized Security Management

All security rules and monitoring are centralized through AWS WAF and CloudFront.

Production Implementation

This architecture was successfully implemented in a production environment, providing:

• Zero security incidents related to direct ALB access
• Improved performance through CloudFront caching
• Reduced load on application servers
• Simplified security monitoring and alerting

The combination of AWS managed services with custom security controls creates a robust, scalable architecture that maintains high security standards while supporting business growth.

Conclusion

Building secure applications requires thinking beyond just code-level security. This multi-layer architecture demonstrates how infrastructure design can provide comprehensive protection through strategic placement of security controls, network isolation, and custom access validation.

The architecture also showcases how CloudFront can eliminate the need for complex multi-region deployments while still providing excellent performance for global users—proving that smart use of AWS managed services can deliver enterprise-grade results with simplified operations.