Understanding Azure Front Door for Application Security
Azure Front Door is a global application delivery network that provides fast and secure content delivery for web applications. It acts as a content delivery network (CDN) and load balancer, optimizing both the security and performance of applications by routing requests to the closest available server. This ensures that users experience minimal latency, regardless of their geographic location.
What is Azure Front Door?
Azure Front Door sits at the edge of Microsoft’s global network and acts as the initial access point for requests to your application. It supports HTTP/2 and WebSocket protocols, allowing applications to stay modern and capable of handling complex, persistent connections. Azure Front Door is highly customizable, allowing companies to define routing rules, enforce HTTPS-only access, and set custom caching policies, all while maintaining robust security measures.
Core Features and Security Capabilities
Web Application Firewall (WAF): Azure Front Door includes a WAF that protects against common security threats, such as SQL injection, cross-site scripting, and distributed denial of service (DDoS) attacks. The WAF is easily configurable and can be set to enforce managed rules, including those based on the OWASP core rule set.
DDoS Protection: By default, Azure Front Door offers protection against DDoS attacks by absorbing large traffic volumes at the edge network, ensuring your backend servers aren’t overwhelmed.
Geo-Filtering and Rate Limiting: These features allow for fine-tuned control over incoming requests. Geo-filtering restricts access to specific regions, while rate limiting prevents abuse by capping the number of requests allowed within a certain timeframe.
Private Link and Custom Headers: For higher security, Private Link ensures that only requests originating from your Front Door can access certain backends. Additionally, custom headers, such as X-Azure-FDID, add an identifier unique to your Front Door, preventing unauthorized access.
Using WAF on Azure Front Door for Threat Protection
Configuring the WAF within Azure Front Door helps guard against malicious attacks that could compromise sensitive information or degrade performance. WAF policies can be set up to either monitor, detect, or block suspicious traffic. Here’s how:
Create and Configure a WAF Policy: In the Azure portal, under Front Door settings, navigate to Web Application Firewall (WAF) policies and create a new policy. Here, you can set rules to allow, block, or monitor requests based on IP address, country, or custom matching conditions.
Apply Rules and Test: Start with detection mode to monitor incoming traffic. This allows you to observe the WAF’s behavior and fine-tune rules before switching to prevention mode for proactive blocking.
Exploring Azure Application Gateway for Regional Security
Azure Application Gateway is a web traffic load balancer that provides load balancing within Azure regions. It can help manage traffic at the application layer (OSI Layer 7) and enables efficient routing, scalability, and increased security.
What is Azure Application Gateway?
Unlike Front Door, which operates at a global level, Azure Application Gateway works regionally within Azure’s virtual networks (VNets), acting as a primary entry point for web traffic at the local level. Application Gateway integrates with Azure Web Application Firewall (WAF), giving added security and control over the application traffic routing and distribution.
Key Benefits: Layer 7 Load Balancing and WAF
Layer 7 Load Balancing: Application Gateway provides URL-based routing, allowing you to route requests to different backend pools based on path, hostname, or query parameters. This is ideal for complex applications where requests for different services (e.g., payment and account sections) are routed to specific servers.
End-to-End Encryption: SSL offloading and SSL pass-through options enable Application Gateway to manage secure connections, with encryption from the user’s device all the way to the backend server.
Integrated WAF Protection: Application Gateway’s WAF can block suspicious traffic at the application level. You can define managed rules (using OWASP standards) or custom rules tailored to your application’s specific requirements.
Combining Azure Front Door with Application Gateway
Using Azure Front Door and Application Gateway together creates a robust multi-layered security model that enhances both global reach and regional security. This combination leverages the strengths of each service to protect and manage traffic on both global and regional levels.
Why Use Both for Multi-Layered Security?
By using Front Door as the global entry point and Application Gateway for local distribution, companies can ensure optimal latency, security, and availability for users worldwide. This approach benefits applications that need high availability and seamless performance while minimizing security vulnerabilities across various regions.
Configuring Traffic Flow: Front Door as the Entry Point
In this configuration, Azure Front Door serves as the initial point of contact, managing incoming traffic and ensuring it routes to the appropriate Application Gateway instance based on region. This setup provides a flexible way to manage global and local traffic requirements with WAF protection in both services.
Addressing Specific Security Needs for Internal Applications
One of the primary concerns for many companies is securing internal-only applications while maintaining flexibility and efficiency in traffic routing. Azure Front Door offers multiple options for IP-based control, while Application Gateway provides a more isolated, private approach within Azure VNets.
Whitelisting Public IPs in Azure Front Door
When you only need certain IPs to access internal applications, whitelisting your company’s public IP with Azure Front Door can be a simple solution. However, this approach comes with risks:
Risk of IP Spoofing: If an external entity can mimic your public IP, they might be able to access restricted resources.
Public Exposure: The application remains technically accessible to the public internet, increasing the potential for unauthorized access attempts.
Using Private Link with Azure Front Door Premium
For a more secure alternative, Private Link in Azure Front Door Premium creates a private endpoint that links directly to your Azure virtual network. This setup ensures that only traffic originating from approved Azure networks can reach your resources, bypassing the public internet entirely.
To enable Private Link:
Create a Private Link Resource: In the Azure portal, go to your Front Door Premium profile and select “Add Private Link.”
Approve Private Endpoint: Approve the endpoint connection from your application backend to restrict access.
This keeps your application traffic isolated within the Azure backbone network, ideal for sensitive internal applications that demand an additional security layer.
Deploying Application Gateway with Private IPs Only
For applications requiring an entirely internal network, deploy Application Gateway with private IPs restricted to your VNet. This prevents any external internet access, with all traffic managed within Azure’s virtual network architecture.
Set Up Application Gateway in VNet: Choose a subnet within your VNet dedicated to Application Gateway. Configure backend pools and routing rules as needed.
Restrict NSG Rules: Use Network Security Groups (NSGs) to permit traffic only from specific internal subnets, ensuring external requests are denied by default.
Best Practices for Securing Internal and External Azure Applications
Securing your applications is an ongoing process that combines Azure’s robust features with best practices to maintain an effective, layered security model. Here are several proven practices:
Layered Security: Combining WAF, Private Link, and VNet Integration
By layering Azure’s security tools, such as Front Door’s WAF, Private Link, and Application Gateway with VNet integration, you enhance your application’s resilience to both external and internal threats. This model also aligns with Zero Trust principles, which demand that no traffic is trusted by default.
At ECS LEAD, we understand the importance of balancing application performance with top-notch security. Our team specializes in creating multi-layered security architectures tailored to the unique needs of each business. Reach out to us if you’d like support with setting up or managing Azure Front Door, Application Gateway, or a combination that suits your specific goals.
Monitoring and Logging with Azure Monitor
Azure Monitor and Azure Monitor logs allow you to track application performance, security events, and other critical metrics across your Front Door and Application Gateway instances. Log analytics can identify suspicious patterns, alerting you to possible threats.
Using Geo-Filtering, Bot Protection, and Rate Limiting
Using geo-filtering and bot protection in Azure Front Door limits unwanted access based on location and filters traffic from known malicious sources. Rate limiting is another critical feature, controlling traffic volume and protecting applications from sudden surges that could lead to outages.
Incorporating these strategies will provide your applications with a resilient, secure, and scalable Azure environment.
