Which vulnerability is required to make SQL injection attacks possible?

The vulnerability required to make SQL injection attacks possible is “improper user input validation by the web application.”

SQL injection attacks occur when an attacker is able to insert or “inject” a malicious SQL query into the input fields of a web application. This is made possible primarily due to the web application failing to properly validate, sanitize, or escape user-supplied input. When the input data is not correctly checked or handled, it can be manipulated to alter the SQL queries executed by the web application, leading to unauthorized access or manipulation of the database.

The other options listed do not directly enable SQL injection attacks:

• Improper SQL database schema: While a poorly designed database schema can lead to various issues, it is not a direct enabler of SQL injection attacks. SQL injection exploits vulnerabilities in how the web application processes user input, not the underlying database schema.
• Improper trust relationship between the web application and the SQL database: This might lead to security issues, but it’s not the primary cause of SQL injection attacks. These attacks exploit how input data is processed by the application before being sent to the database.
• Improper SQL syntax validation by the SQL database: SQL databases typically do not perform syntax validation to prevent SQL injection; they execute the query they receive. It’s the responsibility of the web application to ensure that the SQL queries are properly structured and free of malicious input.