While performing online banking using a Web browser, a user receives an email that contains a link to an interesting Web site. When the user clicks on the link, another Web browser session starts and

Clickjacking overlays invisible UI elements to trick users into clicking something other than what they see; this scenario involves no hidden UI layer or deceptive click target - the malicious action is triggered automatically by loading the page.

Cross-Site Scripting (XSS) injects malicious scripts into a trusted web page that execute in the victim's browser; this scenario does not involve injecting code into the banking site itself.

In CSRF, the attacker crafts a malicious link or page that, when loaded by an authenticated user, causes the user's browser to send unauthorized HTTP requests to a target site - in this case the bank - using the user's active session cookie. The bank cannot distinguish the forged request from a legitimate one because it carries valid credentials. The cat video serves as a decoy while the forged transaction executes in the background using the user's authenticated banking session.

Web form input validation is a defensive control that sanitizes user-supplied data before processing; it is not an attack vector and is unrelated to the session-hijacking mechanism described in this scenario.