What Your Bluetooth Devices Reveal About You » Danny Building Bluehood, a Bluetooth scanner that reveals what information we leak just by having Bluetooth enabled on our devices. If you’ve read much of this blog, you’ll know I have a thing for privacy . Whether it’s running my blog over Tor , blocking ads network-wide with AdGuard , or keeping secrets out of my dotfiles with Proton Pass , I tend to think carefully about what data I’m exposing and to whom. Last weekend I built Bluehood , a Bluetooth scanner that tracks nearby devices and analyses their presence patterns. The project was heavily assisted by AI, but the motivation was entirely human: I wanted to understand what information I was leaking just by having Bluetooth enabled. The timing felt right. A few days ago, researchers at KU Leuven disclosed WhisperPair (CVE-2025-36911), a critical vulnerability affecting hundreds of millions of Bluetooth audio devices. The flaw allows attackers to hijack headphones and earbuds remotely, eavesdrop on conversations, and track locations through Google’s Find Hub network. It’s a stark reminder that Bluetooth isn’t the invisible, harmless signal we treat it as. The Problem Nobody Talks About We’ve normalised the idea that Bluetooth is always on. Phones, laptops, smartwatches, headphones, cars, and even medical devices constantly broadcast their presence. The standard response to privacy concerns is usually “nothing to hide, nothing to fear.” But here’s the thing: even if you have nothing to hide, you’re still giving away information you probably don’t intend to. From my home office, running Bluehood in passive mode (just listening, never connecting), I could detect: When delivery vehicles arrived, and whether it was the same driver each time The daily patterns of my neighbours based on their phones and wearables Which devices consistently appeared together (someone’s phone and smartwatch, for instance) The exact times certain people were home, at work, or elsewhere None of this required any special equipment. A Raspberry Pi with a Bluetooth adapter would do the job. So would most laptops. Devices You Can’t Control What concerns me most isn’t that people choose to have Bluetooth enabled. It’s that many devices don’t give users the option to disable it. Hearing aids are a good example. Modern hearing aids often use Bluetooth Low Energy so audiologists can connect and adjust settings or run diagnostics. Pacemakers and other implanted medical devices sometimes broadcast BLE signals for the same reason. The user can’t simply turn this off. Then there are vehicles. Delivery vans, police cars, ambulances, logistics fleets, and trains often have Bluetooth-enabled systems for fleet management, diagnostics, or driver assistance. These broadcast continuously, and the drivers have no control over it. Even consumer devices aren’t always straightforward. Many smartwatches need Bluetooth to function at all. GPS collars for pets require it to communicate with the owne

Source: Hacker News | Original Link