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Special

Ultrasonic Maffia Call

Ultrasonic Maffia Call

  • #guerillamarketing
  • #newtechnology
  • #ultrasonic
  • #hijack
  • #liveinteraction
  • #outofhome
  • #research
  • #avantgarde
  • #sounddesign
  • #communication

Hit series Mocro Maffia announced the start of its second season on the streaming service Joyn — with an unconventional idea we developed in cooperation with Kolle Rebbe.
Hacking the smartphones of passersby at a bus stop, we made them become a part of the series' action. Their phones seemed to dial a number all by themselves, reaching a dangerously scary gangster who proceeded to warn the passersby about undercover cops, demanded payment or pointed out a drug stash from Rotterdam hidden under the bus stop's waiting bench. Eventually, a city-light poster showing the upcoming second season of Mocro Maffia lit up, revealing the prank — to everyone's great relief.

Hit series Mocro Maffia announced the start of its second season on the streaming service Joyn — with an unconventional idea we developed in cooperation with Kolle Rebbe.
Hacking the smartphones of passersby at a bus stop, we made them become a part of the series' action. Their phones seemed to dial a number all by themselves, reaching a dangerously scary gangster who proceeded to warn the passersby about undercover cops, demanded payment or pointed out a drug stash from Rotterdam hidden under the bus stop's waiting bench. Eventually, a city-light poster showing the upcoming second season of Mocro Maffia lit up, revealing the prank — to everyone's great relief.

To start the call using the passersby's own phones, we exploited a yet unfixed security gap in the devices' voice control software. Employing specially developed and built ultrasonic speakers, we emitted an inaudible voice command which started a video call with the actor playing the gangster:
“Hey Siri, call 0170 **** *** ****”

We stumbled upon the technical foundation for ultrasonic voice commands reading the results of a study conducted by Chinese security experts. Using a custom-developed audio plugin employing filtering and amplitude modulation, we shifted pre-recorded voice commands into the inaudible ultrasonic frequency range. Articles about the ultrasonic communication of bats provided some knowledge about the construction of speakers capable of emitting these frequencies. Building custom speaker arrays, we then projected the ultrasonic sound files at the target devices' microphones with very high sound pressure. Following more than a year of researching, developing and experimenting on various iPhone models and iOS versions, we were eventually able to come up with a reliable system that worked outside of laboratory conditions — making the phones dial the number each time.

The immense technical scope and effort eventually paid off: the feedback is phenomenal. So far, the Ultrasonic Maffia Call won silver at the London International Award, the Radio Advertising Award and the Deutscher Digital Award, as well as bronze at the One Show.