Listen to this Post
Introduction
Ultrasonic cross-device tracking uses high-frequency audio beacons (18–20 kHz) to silently link smartphones, smart TVs, and other devices for targeted advertising or surveillance. This covert method bypasses traditional privacy controls, raising urgent cybersecurity and privacy concerns.
Learning Objectives
- Understand how ultrasonic beacons enable cross-device tracking.
- Detect and block ultrasonic signals using technical countermeasures.
- Implement privacy safeguards against covert audio surveillance.
1. Detecting Ultrasonic Beacons with Python
Command/Tool:
import pyaudio
import numpy as np
CHUNK = 1024
FORMAT = pyaudio.paInt16
CHANNELS = 1
RATE = 44100
FREQ_THRESHOLD = 18000 18 kHz
p = pyaudio.PyAudio()
stream = p.open(format=FORMAT, channels=CHANNELS, rate=RATE,
input=True, frames_per_buffer=CHUNK)
while True:
data = np.frombuffer(stream.read(CHUNK), dtype=np.int16)
fft_data = np.fft.fft(data)
freqs = np.fft.fftfreq(len(fft_data), 1/RATE)
if any(abs(freqs[np.argmax(np.abs(fft_data))]) >= FREQ_THRESHOLD):
print("Ultrasonic beacon detected!")
Step-by-Step:
1. Install `pyaudio` and `numpy`.
- Run the script to monitor microphone input for frequencies ≥18 kHz.
- If detected, the script alerts you to potential ultrasonic tracking.
2. Disabling Microphone Access on Windows/Linux
Windows Command:
Get-AppxPackage | Where-Object {$<em>.Name -like "Skype"} | ForEach-Object {
Add-AppxPackage -DisableDevelopmentMode -Register "$($</em>.InstallLocation)\AppXManifest.xml"
}
Linux Command:
sudo apt-get install pulseaudio pactl list sources | grep -e "Name:" -e "Mute:" Identify active mics pactl set-source-mute <source_name> 1 Mute the mic
Purpose:
Revoking microphone permissions prevents apps from detecting ultrasonic beacons.
3. Blocking Ultrasonic Signals with Audio Filters
Tool: UltrasonicFilter (Linux)
git clone https://github.com/ultrasonic-filter/blocker cd blocker make && sudo ./ultrasonic_blocker --threshold 18000
How It Works:
This open-source tool injects noise-canceling frequencies to disrupt ultrasonic beacons.
4. Auditing Smart TV Permissions
Android TV ADB Command:
adb shell pm list permissions | grep "RECORD_AUDIO" adb shell pm revoke <package_name> android.permission.RECORD_AUDIO
Why It Matters:
Smart TVs often host apps with hidden microphone access.
5. Hardening Browser Privacy
Firefox Config (about:config):
media.navigator.audio.full_duplex = false dom.webaudio.enabled = false
Chrome Flag:
chrome://flags/disable-audio-input
Impact:
Disables Web Audio API, a common vector for ultrasonic tracking.
6. Network-Level Blocking with Pi-hole
Pi-hole Setup:
curl -sSL https://install.pi-hole.net | bash pihole -b -d ads.example.com Blocks ad domains hosting beacons
Effect:
Prevents devices from downloading media containing ultrasonic payloads.
7. Monitoring with Wireshark
Filter for Ultrasonic Traffic:
udp.port == 12345 && frame contains "ultrasonic"
Analysis:
Captures network traffic associated with beacon transmission.
What Undercode Say:
- Key Takeaway 1: Ultrasonic tracking operates undetected by humans but is technically detectable and blockable.
- Key Takeaway 2: Proactive hardening of device permissions and audio settings is critical to mitigating this threat.
Analysis:
The rise of ultrasonic tracking reflects a broader trend in adversarial privacy invasions. Unlike cookies or IP tracking, ultrasonic beacons exploit hardware (microphones) rather than software vulnerabilities. Future regulations may classify this as a “covert surveillance” technique, but until then, technical countermeasures are the primary defense.
Prediction:
Ultrasonic tracking will evolve into ultrasonic fingerprinting, where unique audio distortions in device microphones enable persistent identification—even after permission resets. Expect AI-driven beacon systems to dynamically adjust frequencies, necessitating machine learning-based detection tools.
Actionable Defense:
- Regularly update ultrasonic detection tools.
- Advocate for “audio permission” transparency laws.
- Isolate IoT devices on separate network VLANs.
Tools/References:
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: UgcPost 7358483085602037760 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
