What modular functions does the custom XSS platform's index.js script provide besides cookie theft?

The `index.js` script supports two main modular functions: (1) retrieving user cookies via `document.cookie` and the `Image` object; (2) sending HTTP requests (GET/POST) to internal or external targets, with the response exfiltrated back to the platform's '/data' endpoint. The platform also includes optional screen capture functionality, where a POST to '/screen' sends Base64-encoded image data. This design allows easy secondary development, as noted in the original article.