Combinatorial Methods for HTML Sanitizer Security Testing

HTML sanitization is an essential security feature for web services that incorporate user-generated content, removing the ability of malicious actors to perform injection attacks such as cross-site scripting. Exercising additional scrutiny when choosing such filters is prudent, as any insufficiencies in their design or implementation may lead to widespread exploitation of vulnerabilities. This work presents an approach for applying combinatorial security testing, which offers the unique capability to provide mathematically guaranteed coverage of the language defined by an attack grammar, to HTML sanitizers.