What is SQL Injection?
SQL Injection (SQLi) is a type of web security vulnerability that allows an attacker to interfere with the queries made to a database. It occurs when an application includes unfiltered user input in SQL statements. By exploiting this flaw, an attacker can manipulate the database in ways that were not intended by the developer.
SQL injection attacks can lead to various harmful outcomes, including unauthorized access to sensitive data, data corruption, and even complete database deletion. Attackers often use this method to authenticate using bypass mechanisms or retrieve sensitive information such as user credentials, credit card data, or personal identifiable information.
There are several types of SQL injection, such as in-band SQLi, blind SQLi, and out-of-band SQLi. In-band SQLi is the most common and occurs when the attacker uses the same communication channel for both the attack and the result. Blind SQL injection, on the other hand, does not display output directly, but the attacker has to infer the outcome based on the application’s response. Out-of-band SQL injection relies on the server’s response to send data to an attacker-controlled server.
To prevent SQL injection attacks, developers should employ prepared statements and parameterized queries, validate user inputs, and implement proper error handling. Regular security audits and using web application firewalls also enhance an application's resilience against such vulnerabilities.