𝗪𝗔𝗙 𝗥𝘂𝗹𝗲𝘀 𝗮𝗻𝗱 𝗘𝘃𝗮𝘀𝗶𝗼𝗻
A Web Application Firewall (WAF) acts as a digital security guard for your website. It inspects HTTP traffic to stop attackers before they reach your application.
Traditional firewalls protect your network. A WAF protects your specific web apps. It looks at requests and responses to catch threats like SQL Injection and Cross-Site Scripting (XSS).
How WAFs Work:
- Signature-Based Detection: It looks for known patterns of malicious code.
- Anomaly-Based Detection: It flags unusual behavior, like a sudden spike in requests.
- Reputation-Based Detection: It blocks traffic from known bad IP addresses.
- Behavioral Analysis: It studies user sessions to find malicious intent over time.
WAFs also provide:
- Virtual Patching: It blocks exploits for vulnerabilities while you work on a permanent fix.
- Rate Limiting: It prevents brute-force attacks by limiting requests from a single IP.
- Geo-IP Blocking: It stops traffic from specific geographic regions.
Attackers use evasion to bypass these guards. You must know these tactics:
- Encoding and Obfuscation: Attackers hide payloads using URL, HTML, Base64, or Hex encoding. This makes the code look normal to simple rules.
- HTTP Parameter Pollution (HPP): They send multiple parameters with the same name. This confuses how the WAF and the app read the data.
- Fragmentation: They split a single attack into small pieces across different parts of a request.
- Case Sensitivity: They change the casing of keywords, like uNiOn sElEcT, to avoid simple filters.
- Business Logic Exploitation: They exploit how your specific app works. A WAF might see a valid request, but it is still a theft attempt.
How to stay secure:
- Update your WAF regularly to catch new threats.
- Review your logs to find suspicious patterns.
- Tune your rules to reduce false positives.
- Use layered security. A WAF is one part of a larger defense strategy.
A WAF is a vital tool, but it is not a complete solution. Constant monitoring and tuning are required to stay ahead of attackers.
Source: https://dev.to/godofgeeks/waf-web-application-firewall-rules-and-evasion-49p8