12 Ways Attackers Bypass Prompt Injection Scanners (We Built Defenses for All of Them)

ClawGuard is an open-source regex-based prompt injection scanner that uses 245 patterns across 15 languages with no LLM dependency, achieving F1=99.0%. The article details 12 specific evasion techniques—including leetspeak, zero-width characters, Unicode homoglyphs, and Base64 encoding—and the corresponding preprocessing defenses built to counter each one. These defenses form a multi-stage normalization pipeline that neutralizes attacks before pattern matching occurs.