Which of the following describes Cross-Site Scripting (XSS)?

Cross-Site Scripting (XSS) is accurately described as the malicious execution of scripts within a trusted context. This type of attack occurs when an attacker is able to inject malicious scripts into web pages that are viewed by other users. The injected scripts run in the browser of the user who is viewing the compromised page, exploiting the trust that users have in the website.

This context of execution is particularly harmful because the scripts can manipulate the content of the web page, steal cookies, capture session tokens, or perform actions on behalf of the user without their consent. The effectiveness of XSS attacks hinges on the fact that the scripts run in a trusted environment, taking advantage of the user's trust in the web application.

Other choices do not accurately describe XSS. For instance, firewall technology is intended to prevent unauthorized access to or from a private network, not related to script execution. Encryption techniques, by nature, protect data from being read by unauthorized parties rather than executing scripts, and protocols for secure communication like HTTPS ensure data integrity and security in transit but do not involve script execution issues characteristic of XSS attacks.