This tutorial demonstrates exploiting an SQL Injection vulnerability in Hack The Box’s Appointment web app to bypass authentication and retrieve the flag. It covers steps like scanning for open services with nmap, optional directory brute-forcing with gobuster, crafting an SQLi payload to bypass a login form, and automating the exploit with a Bash script. The article emphasizes the importance of sanitizing inputs on login forms, using parameterized queries or stored procedures, and implementing input validation and Web Application Firewalls to prevent SQL Injection attacks.