What are some exploitation techniques using BHO after gaining system administrator privileges?

Once administrator privileges are obtained, attackers can forge Microsoft Authenticode signatures to make the BHO appear verified, or capture browser POST data (such as plaintext passwords) by handling the `BeforeNavigate2` event. They can also download files through IE's context to bypass firewalls, and inject JavaScript into IE pages. These techniques leverage the BHO's access to browser internals. For code examples, refer to the article: Implementing IE Browser Hijacking Using BHO.