Mastering SQL Injection: From Theory to Exploitation

The Anatomy of a Hack

SQL Injection (SQLi) remains one of the oldest yet most devastating vulnerabilities in the OWASP Top 10. It occurs when an application blindly trusts user input and concatenates it directly into a database query.

When a database receives a query, it compiles it. If an attacker can manipulate the input string to change the structure of that query, they can bypass authentication, exfiltrate data, or even delete entire tables.

The Vulnerable Pattern

Consider this simple Python login function. It takes a username and directly formats it into the SQL string.

# ❌ VULNERABLE CODE
def login(username):
    # The developer blindly trusts the input
    sql = f"SELECT * FROM users WHERE username = '{username}'"
    database.execute(sql)