QA
Intermediate LevelWeb Security & Cyber Defense

What is a Web Application Firewall (WAF) and how does it filter malicious HTTP traffic?

❓ Interview Prompt: Explain Web Application Firewall (WAF), Layer 7 inspection, signature matching, anomaly scoring, ModSecurity, and AWS WAF rule groups.

A Web Application Firewall (WAF) operates at OSI Layer 7, inspecting incoming HTTP request payloads to block cyber attacks before they reach backend application servers:

WAF Capabilities:

•
Signature Matching: Detects known attack patterns (e.g. '<script>', '' OR 1=1', '../etc/passwd').
•
Rate Limiting & Bot Control: Blocks automated bad bot user-agents and IP request bursts.
•
OWASP Managed Rules: Protects against common web vulnerabilities out of the box.

Code Implementation Example

json
// AWS WAF Custom Managed Rule Group Configuration
{
  "Name": "AWSManagedRulesCommonRuleSet",
  "Priority": 1,
  "Statement": {
    "ManagedRuleGroupStatement": {
      "VendorName": "AWS",
      "Name": "AWSManagedRulesCommonRuleSet"
    }
  },
  "OverrideAction": { "None": {} }
}
💡AWS WAF Managed Rule Group configuration JSON.
🎯 Interview Key Takeaway

WAFs inspect Layer 7 HTTP traffic to block XSS, SQLi, and bot attacks before they hit backend application code.

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