SQL injection (SQLi) is a web security vulnerability that allows an attacker to interfere with the queries that an application makes to its database. Historically, it is one of the oldest and most devastating flaws on the Internet. When a SQL injection is successful, an attacker can view data that they are not normally authorized to see.
1. The Different Types of SQL Injection
There are several variants of SQL injection. Classic SQL injection (In-Band) is the most common and easiest to exploit. Blind SQL injection (Blind SQLi), on the other hand, does not return data directly to the screen. The attacker must ask true/false questions to the database.
2. Prevention and Remediation Strategies (OWASP)
- Use of Prepared Statements (Parameterized Queries): This is the most effective defense method. It forces developers to define the SQL code first.
- Rigorous Input Validation: Input validation ensures that only valid data enters the application workflow.
- Principle of Least Privilege: This involves limiting the access rights of the database account used by the web application.
- Effective protection against SQL injections cannot be improvised and requires a systemic approach incorporating code reviews, applied security testing (SAST/DAST/IAST), and a WAF.