Cross-Site Scripting (XSS) is a vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users. These scripts execute in the context of the victim’s browser, enabling various exploitations. Let’s evaluate each option:
Option A ("Steal the user's session identifier stored on a non HttpOnly cookie"): This is possible with XSS. If a session cookie is not marked as HttpOnly (preventing JavaScript access), an attackercan use a script to access document.cookie and steal the session ID, leading to session hijacking.
Option B ("Steal the contents from the web page"): This is also possible. An XSS payload can manipulate the DOM, extract content (e.g., via innerHTML), and send it to the attacker, such as through a GET request to a malicious server.
Option C ("Steal the contents from the application's database"): This is not possible with XSS alone. XSS operates on the client side within the browser’s sandbox and cannot directly access the server-side database. Database access requires server-side vulnerabilities (e.g., SQL injection), which is a separate attack vector. Thus, this exploitation is not feasible through XSS.
Option D ("Steal the contents from the user's keystrokes using keyloggers"): This is possible. An XSS script can inject a keylogger (e.g., using onkeydown events) to capture keystrokes and transmit them to the attacker, especially on pages where sensitive data (e.g., forms) is entered.
Therefore, the correct answer is C, as XSS cannot directly exploit the database. This distinction is crucial in understanding attack vectors, a core topic in the CAP syllabus under "OWASP Top 10 (A03:2021 - Injection)" and "XSS Mitigation."
References: SecOps Group CAP Documents - "OWASP Top 10," "Cross-Site Scripting (XSS)," and "Client-Side Attack Vectors" sections.
