AliExpress accused of fingerprinting shoppers with silent audio trick that also muted a dev's headphones
Sawtooth waves you can't hear still mess with your Bluetooth. Firefox and Brave say they've got you covered
Developer Matt Callaghan discovered that Alibaba was using audio fingerprinting to track web users. When Callaghan visited Alibaba's website, his Bluetooth headphones stopped playing music. The issue persisted across both Firefox and Chrome browsers. Callaghan's investigation revealed two obfuscated audio scripts within Alibaba's browser security and anti-abuse tooling.
These scripts built a WebAudio graph that generated and analyzed a sawtooth waveform, even when the audio was muted. This prevented Bluetooth headphones from switching back to the phone. AliExpress was also collecting data on screen dimensions, device memory, browser plugins, WebGL rendering, and mouse events. Firefox claimed its anti-fingerprinting technology prevented Alibaba's tracking, but Ritter from Firefox explained that as of version 118, anti-fingerprinting protections grouped all users together, making it hard to distinguish individuals.
Brave also responded, stating it protects users from fingerprinting and blocks AliExpress's specific tracking scripts. Firefox and Brave's protection methods work differently, and Chrome's protection is less aggressive.
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