Judy created a forum, one day. she discovers that a user is posting strange images without writing comments. She immediately calls a security expert, who discovers that the following code is hidden be

The code reads and transmits the existing document.cookie value rather than writing or injecting any new cookie into the browser.

The code does not redirect the user - it only sends cookie data as a query string parameter embedded in an image tag src attribute.

The script is not a virus and does not target username or password fields; it specifically harvests session cookies stored in the browser's document.cookie.

The script uses document.cookie to read the victim's session cookie and session ID, then appends them as a URL parameter in an image src pointing to the attacker's submitcookie.php script, which logs the stolen data server-side. This is a classic stored XSS cookie-theft technique that executes silently when the image loads in the victim's browser. The attacker can then use the captured session token to hijack the victim's authenticated session without needing their credentials.