A user discovered that the AliExpress website uses a hidden audio signal to track and create a unique identifier (fingerprint) of their device without consent. This practice, which specialists call 'audio fingerprinting,' was revealed after the user encountered Bluetooth connection issues while using the site.
The code scripts function by interacting with the device's audio hardware to generate a signal and subsequently measuring specific characteristics of its response. This allows for the creation of a device 'fingerprint' without using any cookies and remaining undetected by the user.
Similar code is also used in browser fingerprinting methods, where details characteristic of a specific device are collected and combined to recognize the browser over time.
Brave, the developer of a privacy-focused browser, was the first to challenge AliExpress in a post on the social network X. Brave reported that their browser is capable of blocking such tracking attempts.
The entire process is based on analyzing minute differences in how each computer processes an audio signal. These differences are formed by components such as the computer's processor, sound hardware, operating system, browser, and drivers, leading to the formation of a unique 'fingerprint.'