This tweet suggests a bypass technique for web application firewalls (WAFs) where prepending junk data to the payload can help bypass detection. Unlike relying on content-encoding tricks, the method involves simply adding irrelevant or non-malicious data at the beginning of the attack string. This can confuse the WAF's pattern matching or signature detection, allowing malicious payloads to pass through undetected. This technique is generally applicable to various types of vulnerabilities that WAFs try to mitigate, making it a universal bypass approach. It highlights an important point that WAFs need to carefully parse and sanitize inputs, not just check payloads in isolation. This method can be effective against many vendors if their filtering logic is simplistic and doesn't normalize input properly.
Original tweet: https://twitter.com/DomCyber115839/status/1950063629467828356