Parameterized Queries - OWASP Top 10

Introduction

Parameterized queries are a method of executing SQL queries that helps prevent SQL injection attacks, one of the most critical vulnerabilities identified by the OWASP Top 10. By using parameterized queries, user inputs are treated as data rather than executable code, significantly improving application security.

What are Parameterized Queries?

Parameterized queries, also known as prepared statements, are a way to execute SQL statements where the parameters (or placeholders) are defined in advance, and the actual values are supplied later. This separation ensures that user inputs are not interpreted as SQL code.

How They Work

When a parameterized query is executed, the SQL engine distinguishes between the code and the data. This is achieved through the following steps:

1. Define a SQL query with placeholders (e.g., `?` or named parameters).
2. Prepare the SQL statement, which tells the database to compile the query without executing it yet.
3. Bind the actual values to the placeholders.
4. Execute the query with the bound values.

Code Examples

Below are examples of parameterized queries in different programming languages:

Python (Using SQLite):
import sqlite3

connection = sqlite3.connect('example.db')
cursor = connection.cursor()

# Parameterized query
username = 'user1'
cursor.execute('SELECT * FROM users WHERE username = ?', (username,))
results = cursor.fetchall()
connection.close()

PHP (Using PDO):
$pdo = new PDO('mysql:host=localhost;dbname=test', 'root', '');
$username = 'user1';
$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');
$stmt->bindParam(':username', $username);
$stmt->execute();
$results = $stmt->fetchAll();

Best Practices

• Always use parameterized queries whenever accepting user input in SQL queries.
• Use ORM (Object-Relational Mapping) frameworks that support parameterized queries to simplify database interactions.
• Validate and sanitize user inputs before processing them.
• Educate development teams on the importance of secure coding practices.

FAQ