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SQL Injection (SQLi)

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🛡️ SQL Injection (SQLi)

What is SQL Injection?

SQL injection (SQLi) is a web security vulnerability that allows an attacker to interfere with the queries that an application makes to its database.

🧠 How It Works

An attacker can manipulate input fields or URL parameters to inject malicious SQL code. This can allow them to:

  • View unauthorized data (e.g., other users’ information)
  • Modify or delete data
  • Bypass authentication
  • Execute administrative operations on the database
  • In some cases, compromise the underlying server or perform denial-of-service (DoS) attacks

💬 Example Scenario

Suppose a login form uses the following SQL query:


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

An attacker could input:

  • Username: admin' --
  • Password: (anything)

This results in:


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

The -- sequence comments out the rest of the query, potentially granting access without a valid password.

Impact

SQLi can lead to full database compromise, data breaches, and even remote code execution in severe cases.

🛡️ Prevention Tips

Best Practices

  • Use parameterized queries or prepared statements
  • Employ ORMs (Object-Relational Mappers) that abstract SQL logic
  • Validate and sanitize all user inputs
  • Implement least privilege for database accounts
  • Regularly test for vulnerabilities using tools like SQLMap or Burp Suite

🔗 Resources

Graph View