Computer Science – 6.2 Data Integrity | e-Consult

SQL injection is a security vulnerability that allows attackers to insert malicious SQL code into database queries. Data validation is a crucial defense mechanism against SQL injection. By carefully validating user input, we can prevent attackers from manipulating the query's structure and executing unintended commands.

Vulnerable SQL Query (Example):

SELECT * FROM Users WHERE username = '\$username' AND password = '\$password';

In this vulnerable query, the \$username and \$password variables are directly incorporated into the SQL query. An attacker could provide a malicious username or password containing SQL code, such as: ' OR '1'='1. This would bypass the authentication check and grant unauthorized access.

Validated SQL Query (Example):

To prevent SQL injection, parameterized queries (also known as prepared statements) should be used. Parameterized queries separate the SQL code from the data. The database driver handles the escaping and quoting of the data, preventing it from being interpreted as SQL code. Here's an example using a parameterized query (the specific syntax varies depending on the database and programming language):

SELECT * FROM Users WHERE username = ? AND password = ?;

In this example, the question mark (?) acts as a placeholder for the username and password. The database driver will ensure that the values provided for these placeholders are treated as data, not as part of the SQL query. This effectively neutralizes any attempts at SQL injection.

Benefits of Parameterized Queries:

• Prevents SQL Injection: The primary benefit is preventing attackers from injecting malicious SQL code.
• Improved Performance: Parameterized queries can be cached by the database, leading to improved performance.
• Code Clarity: They make the code easier to read and maintain.