AliExpress tracks users via inaudible sound
The shopping site AliExpress uses an inaudible audio tone through the browser to create a digital fingerprint of users and track them. The technique was exposed after it caused a bug in a security researcher's Bluetooth headphones. It is a relatively aggressive fingerprinting method, but privacy-focused browsers like Firefox and Brave already incorporate defenses against it.
The Chinese shopping site AliExpress uses an aggressive tracking technique: it plays an inaudible audio tone through the browser using the WebAudio API to create a unique digital fingerprint of each user's device. The technique was exposed after an anonymous security researcher, known as laserphile, noticed that his wireless headphones stopped playing audio from his phone every time he visited the AliExpress website in a browser. Code analysis revealed that the site plays a muted sound and analyzes the unique way each computer processes it, based on hardware and software components like the processor and sound card. This creates a unique signature that allows identification and tracking of users even without using cookies. The technique is considered relatively aggressive but is not new. Privacy-focused browsers like Firefox and Brave already incorporate protection mechanisms against this type of fingerprinting. Firefox blocked this specific vector three years ago, and Brave injects random information into the browser output to disrupt the fingerprint.