What are URL parameters, and why can they be a security risk?

URL parameters are indeed data passed in a URL, typically following a question mark, and are used to convey additional information to the server requesting to access a particular resource. Because these parameters are included directly in the URL, they are easily visible and can be manipulated by users.

The potential risk arises from this manipulability. Attackers can alter the parameters to gain unauthorized access to information or perform actions that can compromise the security of a web application. For example, if a URL parameter is used for authentication or to specify a user’s ID, an attacker may modify it to access someone else's account or sensitive data. This is a common vulnerability seen in attacks such as SQL injection or Cross-Site Scripting (XSS), where the attacker exploits poorly sanitized inputs in URL parameters.

In contrast, static data that cannot be changed is not inherently a security risk because it doesn’t allow for manipulation. Hidden parts of a webpage do not directly involve URL parameters, nor do they present the same risks as modifiable data. Lastly, secured information that enhances privacy suggests a protective measure rather than a risk and doesn't accurately describe the nature of URL parameters. Understanding the risks associated with URL parameters is crucial for developers and security professionals working to protect web applications from exploitation.