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Voice-controlled systems like Alexa and Siri can be hijacked by ultrasonic commands

By midian182 ยท 6 replies
Sep 7, 2017
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  1. As voice-controlled devices such as smartphones, vehicle infotainment systems, and smart speakers become increasingly popular, hackers are coming up with innovative ways of targeting them. Now, a team of researchers has shown off a method that uses ultrasonic frequencies – sounds so high that they’re inaudible to humans.

    Scientists from China's Zhejiang University demonstrated the technique, which is aptly called DolphinAttack. First, they created a program that can translate human voice commands into sounds above 20kHz. These were played back using a standard smartphone equipped with an amplifier, ultrasonic transducer, and an extra battery, all of which costs less than $3.

    The commands were tested on 16 devices and seven systems, including Siri, Alexa, Google Assistant, Samsung S Voice, Cortana, and the navigation system in Audi cars. The team said: "the inaudible voice commands can be correctly interpreted by the SR (speech recognition) systems on all the tested hardware."

    In addition to basic commands like “Hey Siri” and “Okay Google,” the exploit can be used in more malicious ways, such as visiting malware-loaded websites or making outgoing calls to spy on victims.

    Thankfully, there are limitations that mean the attack is less than perfect. At the moment, the device is ineffective beyond a range of five or six feet, and it works better in quieter environments; using ultrasonic commands that tell Siri to switch on airplane mode was 100 percent successful in an office but just 30 percent successful in a street. The other problem for hackers is that a digital assistant must be switched on, and most of them respond to commands with a tone or reply of their own, which would likely alert a user.

    While altering a system so it ignores commands over a certain frequency might seem like a simple solution, industrial designer Gadi Amit told FastCompany that doing so could lower its “comprehension score,” while some devices use it for ultrasonic pairing.

    Permalink to story.

  2. seeprime

    seeprime TS Guru Posts: 382   +410

    The ultrasonic signals are referred to as beacons. These need to be turned off in all devices so that their presence does nothing. Windows 10 has an off switch for them, although I understand that 70% of people are ignorant of Windows 10 privacy controls. If Alexa and Siri do not allow beacons to be ignored, I suggest that those devices not be used until the user can regain control over their device. Or lay a dense cloth over it when not using it, to attenuate the signal. A simple firmware or driver update could resolve the issue.
  3. jobeard

    jobeard TS Ambassador Posts: 12,896   +1,530

    this post has links to explain the harmonics generated by the HF for the DolphinAttack
  4. jobeard

    jobeard TS Ambassador Posts: 12,896   +1,530

    WiFi: Beacon frame is one of the management frames in IEEE 802.11 based WLANs. It contains all the information about the network. Beacon frames are transmitted periodically to announce the presence of a wireless LAN. Beacon frames are transmitted by the access point (AP) in an infrastructure basic service set (BSS).

    Bluetooth: see this description

    this PDF is the description from the researchers​
  5. Reehahs

    Reehahs TS Guru Posts: 729   +472

    Great, now you have bats, cats, and rats controlling Alexa, Siri, and Cortana.
  6. seeprime

    seeprime TS Guru Posts: 382   +410

    Thanks for the explanation. Beacons are high frequency transmissions that can be picked up and used to activate functions, such as playing a complementary ad on a tablet when a commercial is on the TV, is this not also the case?
  7. jobeard

    jobeard TS Ambassador Posts: 12,896   +1,530

    IMO, "Beacon" is not the term for this issue - - Yes, the harmonics are being used to trigger ANY voice activated service.

    Beacon is more of an RF signal or a protocol reply as in ping.

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