Is it possible to control Amazon Alexa, Google Now using inaudible commands? Absolutely Eavesdropping appliances like Amazon Echo and software assistants like Google Now can be attacked using mangled words that get interpreted as commands, but humans hear as nonsense. As explained in a 2015 paper [PDF], the phrase "Cocaine Noodles," for example, can be heard by Google Now as its command invocation, "OK, Google …
What does Amazon deliver when you say
"Cocaine noodles"?
Could seriously revolutionise the drug industry. The next Pablo Esteban is probably coding the drug über meets echo app as we speak (unless it's already here and I'm hugely out of touch with how things are done now days).
All delivered by drone of course.
Not so simple if it's the electret capsule. A little easier if it's the FET (need new design of capsule as FET is internal). If it's simply aliasing type "mixing" (Fin - Fsample), then you need a pretty good low pass filter as a simple R C will be defeated by simply more volume. OTOH, if it's aliasing, then sampling at 96kHz and DSP filter is very effective as it's very hard to generate above 48kHz (the nyquist frequency for 96kHz).
These products have MEMS microphones, which are mechanically very linear out towards 100 kHz. It's more likely to be the digitisation process with limited filtering. Sampling at the higher rate is the best solution, as you write, but at the expense of power consumption for the phone.
it is fairly easy to defeat it with a low-pass filter on the microphone.
Now try convincing let's say Google or Amazon to add it to their designs. If you are wondering why they are so reluctant to do so, I suggest running a spectrum analyzer on the audio section of the next TV advert. You will stop wondering when you notice the amount of "interesting" stuff in the higher frequencies.
"suggest running a spectrum analyzer on the audio section of the next TV advert"
Yep, it's done to wake up your tablets and phones, they can pick up the audio and that allows the ad-men to do more tracking by looking for the number of "callbacks"!
Easy answer? Stop watching TV as it's full of shite any way! Ha ha!
... l it is fairly easy to defeat it with a low-pass filter on the microphone ...
You can certainly try to defend against it, but you can't fully protect yourself against an attack of this type. The fourier-aliasing attack aside, any sufficiently loud noise will generate harmonics and sub-harmonics if the microphone has an even slightly non-linear response somewhere within the signal's spectrum. You can do it with the ultrasound as in this report; you can do it with infrasound, or you can do it with a sharp whistle. The ultrasound case is dead easy, as you are relying on the lowest-order non-linearity, and use your microphone to generate a difference frequency of two high-frequency signals. The last two are harder to control to produce the desired output signal, since you are relying on higher-order non-linearities - but still easy enough if you have access to the same hardware the target has.
Depending on where they are placed, low-pass and band-pass filters may defend against the attack (if they are placed before the non-linear element), or they can facilitate it: if the filter is placed after the non-linear element, it will cut the abnormally-strong signal at the unexpected frequency, so that you'll never know anything was wrong in the first place. The already-generated harmonics will just pass through ...
The only sure-fire defence is to completely cut the output if the input at any frequency (measured as early as possible in the device) exceeds the design limits. Naturally, this defence immediately becomes a denial-of-service vulnerability, and so it goes.
There is a serie a "déception challenges" on kaggle like this one:
https://www.kaggle.com/c/nips-2017-non-targeted-adversarial-attack
You have to modify an image so that a human won't notice the difference but certain classifiers will be fooled.
But deep learning is not the only victim. For ages english people ask me about the kind of "messages" i am looking for or to repeat some Peter Sellers lines..
Is this your way of sticking your oar in?
http://www.fyneboatkits.co.uk/photos/products/rowlocks/bronze-open-rowlocks-sockets.jpg
For some reason there's a big increase in popularity of these kits (the 12" version is the most popular for some reason):-
https://images-na.ssl-images-amazon.com/images/I/31krlxYXLhL._SX300_.jpg
And yet it isn't. :-(
Fortunately it's probably impossible to pull off with the standard speaks on a regular phone due to the crappy bandwidth they have.
OTOH Bluetooth it to a custom device and it could still be quite small but still create a lot of mayhem...
The only microphone I have turned on lately is one that intentionally records other sounds. I am using it to answer scammers that ask for your e-mail address.
The nice little Olympus voice recorder then replies:
Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...Gonads are useful for their purpose but they are no substitute for brains...
I have slightly changed my sound wave. I am sending a sound sequence calculated to possibly induce epilepsy like some video games. This is a bit of a hobby for a while since it doesn't cost me anything to send this. I am waiting to see if they change the scam greeting again. The first time the greeting was half an hour long. The next morning they shortened it to 1 minute.
I can also confuse them because I have more than one phone number. The one I am using is not listed and does not accept incoming. It is also a dumb phone on the net. The people that supply my line think this is hilarious. But then they are students (summer job) from the university where I am working.
She don't lie, she don't lie, she don't lie... Propane
https://www.amazon.co.uk/20Vrms-Ultrasonic-Transducer-Sensor-Detector/dp/B00P0BD6PA
https://www.amazon.co.uk/MakerHawk-NodeMcu-Development-ESP8266-ESP-12F/dp/B071S8MWTY
https://www.amazon.co.uk/Value-Charger-Adapter-Quadcopter-XC317/dp/B01F6YUGLW
https://www.amazon.co.uk/XCSOURCE-Battery-Lithium-Charging-TE668/dp/B01N2Z24VL
I'm sure this would be difficult to sneak into a room. It must be all the size of a moderately voluminous matchbox.
A lot of the time those apps simply go dormant in the foreground but the services stay active in the background. You really want to do it properly look for Google free clean builds from sites likes XDA and flash your phone without any of the Google shit in there in the first place, the only way to be sure the services never even got installed let alone started.
The composer Fredrick Chopin exploited an effect like this in some of his compositions. He didn't use intermodulation distortion but the beat effects of many notes played at speed to give the subjective impression of another part being played inside the piece. (Needless to say you need to have rather good technique to achieve this -- you're more likely to hear it on a decent recording of something like his Etudes.)
No need to stay anonymous, we use ours a lot too, so much so we added three dots to the echo we got to celebrate the birthday of baby jesus last year.
Anything it can't find on amazon music (I hit maybe three songs a week that it wants me to upgrade to the premium music jobby for) I just ensure there's a copy on my plex server and it can then pull it from there (it does this automatically if the song is already present in any of my music libraries it can see including online services like spotify.
We've found we use the timer a hell of a lot, the DAB radio only gets turned on for the odd sporting event now (i'm a football fan, not popular around these parts I know) all other radio and music is now consumed via either a dot and a decent speaker, or the echo unit.
We (like many people I think) have disabled the ability for it to buy anything in the settings. This wasn't hidden and wasn't hard. It can still buy media, so the worst I could be stiffed for is a terrible album/song i'd never be forced to listen to.
We use it to build the shopping list for the families needs (it presents this list on the relevant app on your phone, or will yell it at you in the house) meaning whoever it as whatever shop can see what we need, grab it and remove it from the list.
It's not like the thing was a fortune, and it's not like you have to use it or leave it plugged in, but we do and we do. It cost no more than a reasonable compact speaker that doesn't have the other functionality, and we've found we use that functionality a lot. Great bit of kit.
This post has been deleted by its author
the (Cuban) high-powered ultrasonics is a probably following the publicly well known means for transducer coupling (through the faraday) high levels of audio energy into a remote bug, conducted through the TEMPEST/EMSEC shield itself, for powering the bug and then listening to the reflected audio.
does sound a lot in concept like these social media Microphones!
more acronyms at places like this: https://www.sans.org/reading-room/whitepapers/privacy/introduction-tempest-981
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