Spy vs. Spy

A modern study of mic bugs operation and detection

Veronica Valeros

Sebastian Garcia


MatesLab Hackerspace


Audio eavesdropping is a threat 

A brief tour through the last century FM mic bugs

KGB bug

The Thing



Mic Technology Advances

From lasers in the air to malware

Try all the Mics!





Beurer BY


Listening Experiments

Listening Experiments

No need for a van in front of your house

Listening Experiments

Most mics have a lower battery autonomy than advertised

Geolocation Remarks

  • Attackers need to be close

    • Good for you, filters your attackers

    • ​Bad for them, they need to be close

    • Bad for you, they are close

  • Nobody can help from the Internet

    • ​Bad for you

Comparison with Malware

  • A successful malware infection is not guaranteed

  • Malware leaves traces. Others can find the attack.

  • People from the Internet can help with Malware

Comparison with non commercial

  • Battery vs. electricity

  • Transmit vs. storage

  • One-time conversation vs. all the time

  • One time access vs. continuous access

Contact a company if you are in a life-threatening situation



SDR-based, free software detection and location of hidden microphones



USB SDR device


Normal FM Radio Station

Mic F908

Detection Feature

  • Trained thresholds with ~85 experiments

  • Fixed the thresholds for the best detection

Location Feature

Salamandra new features

  • Detect and locate microphones

  • You can use rtl_power to record and send the signal to others with Salamandra

  • Profile your environment in different times and compare

Real Life Experiments

Experiments Methodology

  1. Seeker goes out. Hider hides mic (or not)

  2. Seeker gets in. Speaks passwords. Hider tries to catch them

  3. Measure time to detection

  4. Measure time to location

  5. Measure recall: (passwords heard / total passwords)

Real Life Experiments

Real Life Experiments

Real Life Experiments

Experiments Conclusions

  • Hiding is hard

    • Power, behavior, know your target, physical access

  • Location is hard

  • Listening is hard

  • Detection is fast (w/Salamandra) 

  • Music doesn't hide your voice


  • Audio eavesdropping is a real threat. Don't be fooled.

  • Now you know how it works.

  • Now you know how to protect yourself.


Try Salamandra, find mics.

Advance the field. Help others.


Veronica Valeros



Sebastian Garcia @eldracote


Spy vs. Spy: A modern study of mic bugs operation and detection. BsidesBud

By eldraco

Spy vs. Spy: A modern study of mic bugs operation and detection. BsidesBud

HITB GSEC 2017 presentation of a research about spying microphones and how to detect them. TL;DR: Don't be fooled. Audio eavesdropping is a real threat. We built a free software tool to detect and locate hidden mic bugs.

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