SQL Injection (SQLi) is a critical web security vulnerability that allows an attacker to interfere with the queries that an application makes to its database. It occurs when an application fails to properly sanitize or validate user input before including it in a Structured Query Language (SQL) command. By injecting malicious SQL code into an input field—such as a login form or a search bar—an attacker can trick the database into executing unintended commands.

The impact of a successful SQL injection attack can be devastating:

Data Theft: Attackers can bypass authentication to view sensitive information they are not authorized to see, such as user passwords, personal data, or credit card details.

Data Manipulation: An attacker can modify or delete data within the database, potentially leading to permanent data loss or the corruption of business records.

Identity Theft: By gaining access to user tables, attackers can take over administrative accounts.

Full System Compromise: In some configurations, SQLi can be used to gain access to the underlying server's operating system.

Ethical hackers test for SQLi by entering special characters (like ' or --) into input fields to see if the application returns a database error. Mitigation involves usingPrepared Statements(parameterized queries), which treat user input as data rather than executable code, and implementing strict input validation. Despite being one of the oldest web vulnerabilities, SQLi remains a top threat on the OWASP Top 10 list due to the prevalence of legacy code and poor coding practices.