Azure Web Application Firewall

Azure Web Application Firewall (WAF)

Azure Web Application Firewall (WAF) is a cloud service that helps protect your web applications from common web exploits and vulnerabilities. It acts as a reverse proxy that sits in front of your web applications, inspecting incoming HTTP requests and blocking malicious ones.

What is Azure WAF?

Azure WAF integrates with Azure Application Gateway, Azure Front Door, and Azure CDN to provide centralized security for your web applications. It uses managed rule sets, custom rules, and intelligent threat detection to defend against attacks such as:

SQL injection
Cross-site scripting (XSS)
File inclusion
Command injection
Cross-site request forgery (CSRF)
And many more OWASP Top 10 vulnerabilities.

Key Features

Managed Rule Sets: Pre-configured rulesets from Microsoft and the community (like the OWASP Core Rule Set) that are regularly updated to address new threats.
Custom Rules: Ability to define your own rules based on IP addresses, geographic locations, request headers, query strings, and more for granular control.
Bot Protection: Helps identify and block malicious bot traffic.
Geo-filtering: Restrict access to your web applications based on the geographical location of the client.
Rate Limiting: Prevent denial-of-service (DoS) attacks by limiting the number of requests from a specific IP address.
IP Threat Intelligence: Leverage Microsoft's threat intelligence feeds to block known malicious IP addresses.
Logging and Monitoring: Comprehensive logs for security events and performance metrics, integrated with Azure Monitor and Sentinel for advanced analysis.
Integration: Seamless integration with Azure Application Gateway, Azure Front Door, and Azure CDN.

Deployment Options

Azure WAF can be deployed in conjunction with several Azure services:

Azure Application Gateway WAF: Provides WAF capabilities for applications hosted within your virtual network. Ideal for protecting applications deployed on IaaS or PaaS within Azure.
Azure Front Door WAF: Extends WAF protection to global applications delivered via Azure Front Door. Suitable for globally distributed applications, microservices, and APIs.
Azure CDN WAF: Protects content delivered through Azure Content Delivery Network. Useful for static content protection and DDoS mitigation at the edge.

Getting Started

To configure Azure WAF, you typically follow these steps:

Deploy an Azure Application Gateway or Azure Front Door.
Enable the WAF feature on your chosen service.
Choose between the managed rule sets or create custom rules.
Configure policies for detection or prevention mode.
Monitor WAF logs and alerts.

Note: WAF policies are separate entities that can be associated with multiple Application Gateway or Front Door instances. This allows for centralized management of your security rules.

Example: Creating a Custom Rule

You can create a custom rule to block requests from a specific IP address range. Here's a conceptual example of how you might configure this:


# Example of a custom rule configuration (conceptual)
Rule ID: Block_Malicious_IPs
Priority: 1
Rule Type: Match condition
Condition:
  - Request IP address is in range: 192.168.1.0/24
Action: Block

Tip: Start with WAF in Detection mode to monitor for potential threats without blocking traffic. Once you're confident in your rule sets, switch to Prevention mode for active blocking.

Learn More

For detailed configuration guides, troubleshooting, and advanced scenarios, please refer to the official Azure documentation: