A lazy programmer at a startup was recently fired for sleeping at their cubicle. Angry about being fired and wanting revenge, the programmer accessed the admin panel of the startup's website using a method they had previously programmed into the application before being dismissed. With access to the admin panel, the former employee was able to delete user accounts from the database, causing significant issues for the company. Which of the following options best describes the methodology of the attack?
Backdoor
Ransomware
Rootkit
SQL injection