In web application security, what does "input sanitization" refer to?

Input sanitization refers to the process of cleaning user input to prevent malicious data from being processed by a web application. This procedure is crucial for maintaining security within web applications, as it involves validating and filtering data submitted by users before it is used in any part of the system, such as databases or application logic.

Malicious data, such as SQL injection or cross-site scripting (XSS) payloads, can be introduced through user input if proper sanitization is not implemented. By ensuring that the input meets specific criteria—whether that be ensuring it is of the right type, format, or within certain bounds—developers can mitigate potential security risks and protect the integrity of their systems.

This is vital for web applications, where user input is commonly accepted in forms, through APIs, or any data entry points that could be exploited. Effective input sanitization acts as the first line of defense against a range of attacks, reinforcing the overall security posture of web applications.