This whitepaper is called Modern Web Application Firewalls Fingerprinting and Bypassing XSS Filters.
You can download it from the following link: https://packetstormsecurity.com/files/download/124419/WAF_Bypassing_By_RAFAYBALOCH.pdf
Source: https://packetstormsecurity.com/files/124419/Bypassing-Modern-Web-Application-Firewalls.html