What Is SQL Injection (SQLi)?

SQL Injection (SQLi) is a type of attack where attackers input malicious SQL statement into input field to manipulate database.

This attack targets to applications that fail to properly handle validation, user input, allowing unauthorized access to sensivite data such as password or credit card details, etc.

How SQL Injection Works

When an application directly includes user input in a database query without proper validation, attackers can modify the query’s behavior to input a malicious SQL statement.

For example :

SELECT * FROM users WHERE username = 'admin' AND password = '12345';

An attacker could input:

' OR '1'='1

Resulting in:

SELECT * FROM users WHERE username = '' OR '1'='1' AND password = '';

This always returns true, granting unauthorized access.

Why SQL Injection Matters in Cybersecurity

SQL Injection is the most dangerous and oldest technique in cybersecurity. This type of attack is consistently listed in the OWASP Top 10.

Even small vulnerabilities allow an attacker to :

• Access, modify, or delete data
• Bypass authentication
• Execute administrative operations on the database.
• Compromise the entire system.

Common Types of SQL Injection

• Classic SQLi : Direct injection via web forms or URL parameters.
• Blind SQLi : Attackers infer database information indirectly (e.g., via error messages or response time).
• Union-based SQLi : Uses the UNION operator to combine results from multiple queries.
• Error-based SQLi : Relies on database error messages to extract information.
• Time-based Blind SQLi : Exploits server response delays to guess query results.

How to Prevent SQL Injection

1. Use Parameterized Queries (Prepared Statements)

Ensure SQL commands treat user input as data, not executable code.

cursor.execute("SELECT * FROM users WHERE username = ?", (username,))

2. Input Validation and Sanitization

Validate all input from users, only allowing expected characters.

3. Use ORM frameworks

Frameworks like Prisma, Hibernate, etc, reduce direct SQL handling.

4. Least Privilege Principle

Limit user permission, only give permission that is needed.

5. Regular Security Testing

Use application security testing tools like SAST, DAST or IAST to detect injection flaws early.

Example in the Real World

An online store website suffered a breach where attackers used an SQL injection in a login form to extract credit card details from its database.

Related Terms

• XSS (Cross-Site Scripting)
• DAST (Dynamic Application Security Testing)
• OWASP Top 10
• Application Security Testing