WebUSB Fingerprinting: Principles, Risks, and Protection Strategies

Introduction: From Hardware Communication to Privacy Tracking

The WebUSB API is a W3C-standardized interface that allows web applications to communicate directly with hardware devices via the USB protocol. Previously, such operations could only be performed by native applications, but the advent of WebUSB enables browsers to control USB drives, smart cards, sensors, and even cryptocurrency hardware wallets. However, this convenience has also given rise to a new tracking technique—WebUSB fingerprinting. It leverages device descriptor information, serial numbers, vendor IDs, and product IDs returned by the WebUSB API to construct a unique user fingerprint, thereby bypassing traditional fingerprinting methods such as cookies and Canvas.

For cross-border e-commerce operators, social media marketers, and users who need to manage a large number of accounts, WebUSB fingerprinting may lead to association of different accounts on the same device, posing a risk of account bans. This article will delve into the working principles of WebUSB fingerprinting, real-world threats, and provide practical protection measures.

Technical Principles of WebUSB Fingerprinting

1. What is the WebUSB API?

WebUSB is a JavaScript interface that allows a webpage to request connection to an authorized USB device via navigator.usb.requestDevice(). Once authorized, the webpage can read a series of information such as device descriptors, configuration descriptors, and interface descriptors. This information includes a large amount of hardware-coded features:

• vendorId: A 16-bit identifier assigned by USB-IF, e.g., 0x8086 for Intel.
• productId: The identifier for the device model.
• iSerialNumber: Most USB devices expose a unique serial number (if supported).
• bcdDevice: The firmware version.

Even if the device is unplugged and re-plugged, these hardware-level IDs usually remain unchanged. After the first user click authorization, a webpage script can query device information at any time (as long as the connection is not broken), and can even detect whether a device is present through periodic polling, thereby determining the user’s physical hardware combination.

2. Uniqueness of Fingerprints

Unlike traditional Canvas or WebGL fingerprints, WebUSB fingerprints do not depend on the browser environment or operating system; instead, they directly capture unique identifiers at the hardware level. For example:

• A user simultaneously connects a Logitech mouse (vendorId=0x046d), an HP printer (vendorId=0x03f0), and a YubiKey (unique serial number).
• The combination of these three pieces of information is virtually impossible for another user to replicate, thus enabling the construction of a high-precision fingerprint.

Research data shows that in a typical user environment with 3 USB devices, the distinguishability of WebUSB fingerprints can reach over 99.7% (source: IEEE S&P 2021 paper “USB Fingerprinting”).

Real-World Threats of WebUSB Fingerprinting

1. Cross-Domain Tracking

Since USB device information is not bound to a domain, and it is difficult for users to completely clear authorizations for each device (re-authorization requires physical plugging/unplugging), attackers can use the same USB device information across multiple websites to associate the same user. For example:

• When a user logs into a social media account on website A, the vendorId + serial number of a Logitech mouse is collected.
• When the user visits website B (another e-commerce platform) with the same browser, website B also scans the device via the WebUSB API and matches the same serial number, thereby determining it is the same user.

Impact on multi-account operators: If you simultaneously log into multiple Amazon or Facebook accounts on the same computer, you might previously avoid association through port isolation and IP isolation. However, WebUSB fingerprints “pierce through” these isolation measures because hardware information is shared at the physical layer. Once detected, the platform may directly ban all associated accounts.

2. Passive Device-Level Tracking

A more stealthy method is that malicious websites do not actively request device authorization; instead, they listen to the navigator.usb.getDevices() method (which requires no user interaction) to obtain the list of devices currently authorized for this domain. If a user has ever authorized a USB device on some website, another website can induce the user to click the authorization dialog (via a targeted request) to obtain the device information. This “secondary authorization” often tricks users into thinking it is normal interaction, thereby leaking privacy.

How to Detect and Prevent WebUSB Fingerprinting

1. Browser-Level Protection

• Firefox disables the WebUSB feature by default; it can be completely turned off via the dom.webusb.enabled setting.
• Chrome and other Chromium-based browsers provide permission control: users can go to chrome://settings/content/usbDevices to view and revoke all site authorizations for USB devices.
• Using “Incognito Mode” or “temporary containers” does not block WebUSB fingerprints because hardware information does not rely on browser storage.

2. Virtual Machine and Containerization Solutions

Some advanced users use virtual machines (e.g., VMware, VirtualBox) to create an independent environment for each account. However, by default, the virtual machine passes through the host’s USB devices to the guest, which still exposes the device serial number. You need to disconnect passthrough before connecting the device, or use virtual USB devices without serial numbers. This process is complex and affects efficiency.

3. Professional Fingerprint Browsers: Effectively Freeze Hardware Fingerprints

For cross-border e-commerce practitioners who need to manage dozens or even hundreds of accounts simultaneously, the most reliable solution is to use a deeply fingerprint-modified browser. Such a browser can simulate or replace USB device information, making each browser window present completely different hardware characteristics.

NestBrowser has made targeted optimizations in preventing WebUSB fingerprints. It not only supports traditional isolation of canvas, fonts, timezone, and IP, but also provides a custom USB device list feature. Users can pre-set which USB devices should be exposed in each environment (or completely block WebUSB API requests), thereby preventing real hardware information from being collected by websites.

For example, on the same physical computer, in the browser environment configured for account A, WebUSB detects a “Logitech G102 mouse”; in the environment for account B, it detects a “Microsoft Designer mouse”. Since each window runs in an independent sandbox, their WebUSB fingerprints are completely isolated. This is one of the core values of NestBrowser: blocking hardware-level association from the bottom up.

Practice: Configuring WebUSB Protection in NestBrowser

Step 1: Create an Independent Environment

Log in to the NestBrowser console, click “New Browser Environment”. In “Advanced Settings”, find the “USB Device Simulation” option.

Step 2: Customize USB Fingerprint

• Enable USB Device Simulation: After checking, you can choose “Simulate Fixed Device” or “Random Device”.
• Fixed Device Mode: Manually specify the vendorId, productId, and serial number (you can even generate random serial numbers as long as they do not expose real ones).
• Random Device Mode: Automatically generate a random set of USB fingerprints each time the window is opened, suitable for scenarios requiring a large number of environments with low consistency requirements.

Step 3: Test the Effect

Open a target website (e.g., Amazon backend) and test using the JavaScript command navigator.usb.getDevices(). You will see that each environment returns simulated devices, not real hardware information. Even when multiple accounts are logged in simultaneously, the platform cannot associate them via USB fingerprints.

Note: In some scenarios, actual connection of a USB keyboard or mouse is required for verification (e.g., certain bank U-shield authentication). In such cases, you can temporarily disable USB simulation and use real devices. NestBrowser supports flexible switching without affecting normal business.

Future Trends: The Game between WebUSB and Privacy

The WebUSB standard is still evolving. W3C has discussed adding restrictions on the “user authorization lifecycle”, such as requiring re-authorization for each page load. Even so, tracking is still possible during the authorized session period. Hardware manufacturers may gradually remove fixed serial numbers during production, but eliminating fingerprinting possibilities entirely is unlikely—because the combination of devices itself is unique.

For industries that rely on multi-account operations, embracing anti-fingerprinting technology in advance is a wise choice to reduce risk. Besides WebUSB, APIs such as WebBluetooth, WebHID, and WebNFC can also be used for fingerprint collection. Comprehensive fingerprint browsers like NestBrowser have gradually covered these emerging fingerprint vectors and continuously updated the rule base, providing users with a “configure once, stay worry-free long-term” experience.

Conclusion

WebUSB fingerprinting is the “invisible killer” in the privacy battlefield. It exploits users’ habitual trust in hardware authorization to quietly establish long-term tracking identifiers. As account operators, you cannot rely solely on traditional IP and cookie isolation; you must recognize the penetrating power of hardware-level fingerprints.

From technical principles to practical deployment, this article provides a complete cognitive framework and solution. If you are looking for a tool that can truly cut off hardware association, consider learning more about NestBrowser—it is trustworthy in both the depth of fingerprint isolation and ease of use. Act now to build a unique digital identity for each of your accounts.