**What is AWS WAF? **

AWS WAF (Web Application Firewall) is a firewall that protects web applications running in AWS environments from unauthorized access.

Specifically, AWS WAF can be integrated with Application Load Balancers (ALBs), API Gateway, CloudFront, and more to prevent injection attacks (SQL injection, XSS), DDoS attacks, and more.

Key Features of AWS WAF

1. Web Request Filtering (Rule-Based Security)

AWS WAF can analyze web requests and allow, block, and monitor based on specific rules, such as:

• IP-based filtering: block/allow specific IP or CIDR ranges
• GeoIP filtering: allow/block requests from specific countries
• HTTP Header Inspection: Analyzes User-Agent and Referer to detect malicious requests
• Query ring inspection: blocks requests containing SQL injection and XSS patterns
• URI inspection: Blocks access to specific paths (e.g., /admin, /wp-login.php, etc.)
• Bot Control: Block malicious bots

2. AWS Managed Rules

AWS WAF provides predefined Managed Rules from AWS and third-party providers.

• AWS Provision Rules
  Core Rule Set (CRS): Common OWASP-based attack defense
  SQL Database Rule Set: Detecting SQL Injection
  XSS Rule Set: Blocking Cross-Site Scripting Attacks
  WordPress Rules: Blocking Attacks Targeting WordPress Vulnerabilities
  Rules are provided according to these environments.
• Third-party provision rules
  You can set up additional security rules provided by security companies such as F5, Fortinet, and Trend Micro.

3. Custom Rules

AWS WAF allows you to create your own security rules in addition to the managed rules described above.

• Regex Matching: Attack detection using regex
• Rate-Based Rule: Blocks IPs that send a large number of requests within a certain period of time (e.g., blocking if there are more than 1000 requests in 5 minutes)
• Custom Response: Returns a customized HTTP response for a specific request (e.g., 403 Forbidden)

4. DDoS protection with AWS Shield

AWS WAF integrates with AWS Shield Standard and AWS Shield Advanced to provide application layer (L7) DDoS attack protection.

• Shield Standard: Basic DDoS protection (free)
• Shield Advanced: AI-powered DDoS detection and response, cost protection (paid)

AWS WAF Cost System

The usage fee for AWS WAF is mainly determined by the following configuration.

One WebACL: $5/month per rule: $1/month Per 100 requested traffic: $0.60

While it can be effective on a small scale, you need to consider the cost when using it in a large service.

Conclusion

AWS WAF is a very important tool for basic security measures in cloud environments. Proper configuration can prevent common vulnerability attacks such as SQL injection and XSS, significantly improving application security. Another great benefit is that AWS Managed Rules makes it easy to adopt defenses against the latest threats.

On the other hand, proper rule design and regular log analysis are essential for effective AWS WAF operation. Especially if you operate a large system, you need to consider optimizing custom rules and DDoS protection. By considering working with AWS Shield, you can also build a stronger defense.

Security measures are not set up once and end, but must be strengthened while constantly responding to the latest threats. Therefore, appropriate management is required according to the company's operational system. If you're unsure about implementing or operating AWS WAF, seeking professional help is one option.

If you want to achieve a higher level of security operations, you should also consider Colorkrew Security's SOC services. Our cloud security professionals can help you protect your systems optimally.