Browser fingerprinting hides in the most unlikely placesMonitoring orgs · 23.08.2026
Online surveillance stopped being just about cookies a long time ago. A far less visible but much more persistent tool is browser fingerprinting: a set of technical device characteristics combined into a unique user "fingerprint." The technology was created mainly for commercial purposes — fraud prevention, scoring, targeted advertising. But it can just as easily serve political surveillance — states and intelligence agencies benefit from tracking people regardless of whether they clear cookies or not. A fresh example of what this looks like in practice was found by a developer digging into a mysterious bug with his headphones.
You open the AliExpress homepage — and the music on your phone cuts out. Not a video, not an ad, just silence. One developer decided to figure out why, and found something more interesting than an ordinary bug.
The issue was with his multipoint Bluetooth headphones: normally the PC has priority, and the phone plays music when the computer is quiet. But as soon as he opened AliExpress in Firefox or Chrome, the music from the phone would go silent within seconds. Close the tab — everything came back. Muting the tab, the browser, or the sound in Windows didn't help. There were no audio or video tags on the page, and Media Session showed the status "none." Formally, there was nothing to play.
The answer was found through the Web Audio API. The page was quietly creating two AudioContext instances — from scripts apparently belonging to Alibaba's anti-fraud toolkit. Both built a chain: a sawtooth oscillator → an analyzer → a script processor → a gain node set to zero → all connected to system audio output. The volume was zero, but the browser was diligently and continuously processing the audio graph, as if live sound processing were happening. This, apparently, was what kept the Bluetooth channel open, preventing the headphones from switching to the phone. The regular mute button was powerless here: there was nothing to mute, since there was no element. There's already an open bug report about this in Firefox's Bugzilla.
But that's just the tip of the iceberg. The same scripts contained checks for canvas and WebGL, screen size, pixel density, number of CPU cores, device memory, installed plugins, supported formats, WebRTC behavior, mouse movements, scrolling, device tilt, and signs of browser automation. In other words, the audio trick is just one of dozens of parameters used for full-fledged device fingerprinting: different browsers, OSs, and hardware process the same audio signal slightly differently, and these micro-differences can identify a device even without cookies. The collected data is encrypted and sent to Alibaba's servers — the author couldn't find out exactly what happens to it afterward, but suspects it's either a persistent device identifier or one of the signals for anti-fraud scoring.
AliExpress's logic is understandable: the platform is fighting account takeovers, fake registrations, scraping, automated purchasing, payment fraud, review manipulation, and abuse of new-user promo codes. At the same time, like any large business, the company also uses this data for marketing. Cookies are unreliable for these purposes — they can be cleared, replaced, copied. But a fingerprint assembled from dozens of independent technical measurements of a device is much harder to fake or erase — and that's the whole crux of the problem. Technology that makes the internet "safer" for business simultaneously makes the user far more transparent — without their knowledge or consent, covertly exploiting even such unexpected channels as a device's audio system. And if it's used for anti-fraud purposes today, what guarantee is there that far less benign clients won't adopt the same method tomorrow?
Source:
https://blog.laserphile.com/2026/08/aliexpress-webpage-keeping-multipoint.html