(quarkslab.com) Web Application Firewall Bypass Techniques: From Misconfiguration Exploitation to Polymorphic Payload Obfuscation

[orlysec@swecyb.com]

(quarkslab.com) Web Application Firewall Bypass Techniques: From Misconfiguration Exploitation to Polymorphic Payload Obfuscation

WAF bypass techniques exploit misconfigurations & parsing discrepancies between WAFs and backends. Key vectors: direct origin exposure (passive DNS, favicon hashes), header spoofing (X-Forwarded-For), request body size limits (8KB–1GB), ASN trust exclusions. Obfuscation methods include lexical (JSFuck, Unicode), structural (HTTP param pollution), and protocol (charset switching, multipart parsing—see WAFFLED). Polymorphic payloads combine techniques to evade ModSecurity/OWASP CRS, Cloudflare, AWS WAF. WAFs ≠ secure coding; validate via offensive testing.

Source: http://blog.quarkslab.com/in-waf-we-should-not-trust.html

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