The Hardware Bridging Threat
Google Chrome supports an advanced API known as WebUSB. This API allows web applications to communicate directly with physical USB devices plugged into your computer—such as specialized scientific equipment, 3D printers, or custom firmware flashing tools. While incredible for browser-based hardware control, it is a massive security vulnerability. Malicious websites can exploit this direct bridge to silently probe your computer for attached USB hardware, attempt to read data from unencrypted thumb drives, or flash malicious firmware onto vulnerable peripherals. You must paralyze this API.
How to Block USB Device Access Globally
You can permanently sever the browser’s ability to interface with your USB ports via Chrome’s Site Settings.
- Open the Google Chrome desktop browser.
- Click the three vertical dots (â‹®) in the top right corner and select Settings.
- In the left-hand sidebar, click on Privacy and security.
- In the main window, click on Site settings.
- Scroll down to the “Permissions” heading and click to expand Additional permissions.
- Click on USB devices.
- Under the “Default behavior” heading, select the radio button for “Don’t allow sites to connect to USB devices.”
Total Port Isolation
The change takes effect instantly. Google Chrome will completely sever its internal connection to your operating system’s raw USB driver stack. The browser is now permanently blind to any peripheral hardware plugged into your machine (excluding standard mice and keyboards). If a website attempts to execute a WebUSB script to scan for attached devices, the API call will instantly auto-reject in the background, returning a null value. This guarantees absolute physical isolation between unverified web code and your physical USB ports.