Simple key event listeners can be bypassed by autofill or password managers. More sophisticated keyloggers don't just listen for keyboard events; they poll the DOM. Every 100 milliseconds, the script checks the value attribute of every input field on the page. If the value has changed, it calculates the difference (the new characters) and logs those. This method catches pastes, drag-and-drop text, and autofilled credentials.
This isn’t theoretical. Several high-profile extensions have been caught keylogging: keylogger chrome extension work
Chrome’s security model isn’t broken—it’s permission-based. The extension above explicitly asks for host_permissions: ["<all_urls>"]. When you install it, Chrome shows a warning: “Read and change all data on all websites.” Simple key event listeners can be bypassed by
Most users click “Add extension” without reading that line. That single click grants the keylogger full legal access. If the value has changed, it calculates the