SQL Injection is one of the most notorious and dangerous vulnerabilities in web applications. It allows attackers to manipulate a website’s database by injecting malicious SQL code. Let’s break it down:
💉 What Is SQL Injection?
SQL Injection (SQLi) is a code injection technique that exploits vulnerabilities in an application’s database query logic. By inserting or “injecting” malicious SQL statements into input fields, attackers can:
- View sensitive data
- Modify or delete records
- Execute administrative operations
- Bypass authentication
- Even take full control of the database
🧠 How It Works
- User Input: The attacker finds a form field (like a login box or search bar) that interacts with the database.
- Injection: Instead of normal input, they enter SQL code.
- Execution: If the application doesn’t properly sanitize input, the database executes the malicious code.
🧪 Example
Suppose a login form uses this query:
SELECT * FROM users WHERE username = 'user' AND password = 'pass';
An attacker enters:
- Username:
admin' -- - Password: (anything)
The query becomes:
SELECT * FROM users WHERE username = 'admin' --' AND password = 'pass';
The -- starts a comment, so the password check is ignored. The attacker logs in as admin without knowing the password.
🎯 What Attackers Can Do
| Attack Type | Description |
|---|---|
| Authentication Bypass | Log in without valid credentials |
| Data Exfiltration | Steal personal or financial data |
| Data Manipulation | Insert, update, or delete records |
| Remote Code Execution | In rare cases, execute system commands |
| Full Database Takeover | Gain admin access to the entire database |
🛡️ How to Prevent SQL Injection
-
Use Prepared Statements (Parameterized Queries)
Safely separate SQL logic from user input. -
Input Validation and Sanitization
Reject or clean unexpected characters like',;, or--. -
Use ORM Frameworks
Object-Relational Mapping tools like SQLAlchemy or Hibernate abstract away raw SQL. -
Limit Database Privileges
Ensure web apps use accounts with minimal access. -
Web Application Firewalls (WAFs)
Detect and block suspicious SQL patterns.
🔍 Real-World Impact
SQL Injection has been behind some of the biggest data breaches in history. For example, the 2008 Heartland Payment Systems breach exposed 130 million credit card numbers—all due to SQLi.
