Bluehood

lastmod 2026-02-18created 2026-02-181 edits

A Bluetooth scanner built to test what information is exposed externally while Bluetooth is enabled

About

Built and released Bluehood, a Python-based scanner that collects nearby Bluetooth signals and visualizes the information users unknowingly expose
Simply leaving Bluetooth on can allow life patterns such as "times when the house is empty", visit history, and more to be tracked
Some medical devices, vehicles, smartwatches, etc. do not let users turn off Bluetooth, so they broadcast signals continuously
Even privacy-focused apps like Briar and BitChat require Bluetooth to be enabled, creating a contradiction between security and exposure
Emphasizes the need to recognize and control the digital traces leaking from everyday devices

Bluehood is a Bluetooth scanner built to test what information is exposed externally while Bluetooth is enabled
- Detects nearby devices and analyzes their appearance/disappearance patterns
- Developed with the help of AI; the goal is to understand the reality of personal information exposure
Developed right after KU Leuven researchers disclosed the WhisperPair vulnerability (CVE-2025-36911)
- The flaw allows hundreds of millions of audio devices to be remotely hijacked or location-tracked
- Cited as an example showing that Bluetooth signals are never harmless

Smartphones, laptops, vehicles, medical devices, etc. always have Bluetooth on
- The notion that "if you have nothing to hide, you have nothing to fear" is widespread
However, simply leaving it on causes unintended information exposure
- For example, running Bluehood in passive mode detected the following
  - When delivery vehicles arrive and whether it is the same driver
  - Neighbors' daily patterns
  - Combinations of devices that appear together (e.g., a phone and a smartwatch)
  - A specific person's commute times
- Detection is possible with just a Raspberry Pi or an ordinary laptop

Some devices do not let users turn off Bluetooth
- Hearing aids use BLE for remote adjustment and diagnostics
- Medical implants such as pacemakers also broadcast BLE signals
- Vehicles and other transport continuously transmit Bluetooth for fleet management and diagnostics
Smartwatches, pet GPS collars, fitness equipment, etc. also cannot work without Bluetooth

Briar syncs messages over Bluetooth/Wi-Fi mesh networks even when the internet is down
- Supports communication for activists and journalists without a central server
BitChat is a decentralized messenger based entirely on a Bluetooth mesh network
- Delivers messages over multiple hops without internet, servers, or phone numbers
Both apps aim to protect privacy, but require Bluetooth to be enabled to use
- As a result, the means of protection simultaneously becomes an exposure path, a contradiction

Personal behavior can be tracked from Bluetooth signal patterns alone
- For example, scanning a specific area for a few weeks can reveal the following
  - Times when the house is empty
  - Whether there are regular visitors
  - Work shift patterns
  - When children come home
  - How often the same delivery driver visits
Logs make it possible to trace back which devices were nearby at a given time
- e.g., the smartwatch of a person out on a walk, a vehicle's tracking device, etc.
This shows how easily everyday digital traces can be collected

A Python application that can run on any device with a Bluetooth adapter
- Continuous scanning to detect nearby devices and identify manufacturers and BLE service UUIDs
- Pattern analysis for hourly heatmaps, dwell time, and detection of related devices
- Randomized MAC address filtering to account for the privacy features of modern devices
- Supports real-time monitoring via a web dashboard
Stores data in SQLite and provides push notifications via ntfy.sh
Can be installed via Docker or manually; runs with root privileges or as a systemd service

Bluehood is an educational demonstration tool, not a hacking tool
- Shows how easily personal information can be exposed even with ordinary hardware
Even for simple convenience features, one should recognize the cost of enabling wireless radios
Urges conscious usage decisions by distinguishing cases where Bluetooth is essential from those where it is merely convenient
If users rethink their Bluetooth habits through Bluehood, the project has achieved its goal

author Zer0 sitemap