I simply do not expose critical switches to Siri from Home Assistant.
Using ultrasound attack to disarm a smart-home system
11–20 of 37 posts
Re: Using ultrasound attack to disarm a smart-home system
#12Why the heck wouldn't they have the wake-word listener confine itself to human-audible frequency ranges? Seems like that would be a really simple fix with zero loss of real-world functionality....
That's on purpose. They created a specific inaudible frequency that the Alexa listens for which causes it to ignore the wake word. This is how they keep from annoying everyone and also blowing up their own servers if, for example, they want to run an Alexa commercial during the Superbowl.
Re: Using ultrasound attack to disarm a smart-home system
#13Why the heck wouldn't they have the wake-word listener confine itself to human-audible frequency ranges? Seems like that would be a really simple fix with zero loss of real-world functionality....
That's on purpose. They created a specific inaudible frequency that the Alexa listens for which causes it to ignore the wake word. This is how they keep from annoying everyone and also blowing up their own servers if, for example, they want to run an Alexa commercial during the Superbowl.
Listening on inaudible words surely are not on purpose?
Listening in on a frequency to disable word detection is a whole other thing...
Re: Using ultrasound attack to disarm a smart-home system
#14I simply do not expose critical switches to Siri from Home Assistant.
I only have Siri kick in when I press the button.
Re: Using ultrasound attack to disarm a smart-home system
#15This makes me wonder if the research was inspired by the clever "prompt injection" attacks in the ChatGPT/LLM world (or vice versa).
Of course. And even the attack itself was proposed by chatgpt.
Re: Using ultrasound attack to disarm a smart-home system
#16Why the heck wouldn't they have the wake-word listener confine itself to human-audible frequency ranges? Seems like that would be a really simple fix with zero loss of real-world functionality....
That's on purpose. They created a specific inaudible frequency that the Alexa listens for which causes it to ignore the wake word. This is how they keep from annoying everyone and also blowing up their own servers if, for example, they want to run an Alexa commercial during the Superbowl.
> Reddit user aspyhackr may have figured out the trick Amazon uses here. Apparently, the Alexa commercials are intentionally muted in the 3,000Hz to 6,000Hz range of the audio spectrum, which apparently tips off the system that the “Alexa” phrase being spoken isn’t in fact a real command and should be ignored.
Seems to be the inverse - if the wake word _lacks_ these frequencies, then Echos ignore it.
Re: Using ultrasound attack to disarm a smart-home system
#17> It's also worth noting that the length of malicious commands must be below 77 milliseconds — that's the average reaction time for the four voice assistants across multiple devices. I don't get it. Why? You can speak to smart assistants much longer than that isn't it?
What I'm wondering is how a useful command can be expressed in 77 ms?
Re: Using ultrasound attack to disarm a smart-home system
#18They tried this before on a smart-hotel in Havana.
Re: Using ultrasound attack to disarm a smart-home system
#19Why the heck wouldn't they have the wake-word listener confine itself to human-audible frequency ranges? Seems like that would be a really simple fix with zero loss of real-world functionality....
It might be that although the sound is inaudible to humans, it gets distorted around and inside the device, and that distorted sound is at audible frequencies that the alexa microphone picks up. Something like how these ultrasonic directional speakers work: https://www.holosonics.com/what-makes-a-sound-source-directi...
Re: Using ultrasound attack to disarm a smart-home system
#20Quite sure the microphones on any smart speaker or phone do not have the build quality to 'hear' near ultrasonic audio.