📖 Introduction

SQL Injection is one of the most dangerous and common web security vulnerabilities. It allows attackers to manipulate database queries and access sensitive data.

🔍 What is SQL Injection?

SQL Injection occurs when user input is directly inserted into a SQL query without proper validation or escaping.

SELECT * FROM users WHERE username = 'user' AND password = 'pass';

If not protected, attackers can modify this query.

⚠️ Real Example

Input:
' OR 1=1 --

Query becomes:
SELECT * FROM users WHERE username = ' OR 1=1 --

This returns all users and bypasses authentication.

💥 Types of SQL Injection

• Authentication bypass
• Data extraction
• Blind SQL Injection
• Error-based SQL Injection

🛡️ How to Prevent SQL Injection

1. Use Prepared Statements

$stmt = $conn->prepare("SELECT * FROM users WHERE username=?");

2. Validate Input

Never trust user input. Always sanitize data.

3. Use ORM or frameworks

They handle escaping automatically.

4. Limit database permissions

Do not use admin-level database users.

❌ Common Mistakes

• Using raw SQL queries
• Trusting GET/POST input
• Not escaping strings

🧪 How to Test for SQL Injection

You can simulate requests using your API testing tool:

📊 Real-World Impact

Many major breaches were caused by SQL Injection, exposing millions of records.

❓ FAQ

Q: Is SQL Injection still relevant?
Yes, it remains one of the top vulnerabilities.

Q: Can HTTPS prevent SQL Injection?
No, HTTPS encrypts data but does not prevent attacks.

Q: Are prepared statements enough?
They are the most effective protection.

🏁 Conclusion

SQL Injection is dangerous but preventable. Always validate input and use secure coding practices.