27 ms·

But there’s still a security flaw in this method. If somebody from Amazon will decide to record you, they just send a reboot command to Echo. After reboot mic’s

by bobuk 6y ago

But there’s still a security flaw in this method. If somebody from Amazon will decide to record you, they just send a reboot command to Echo. After reboot mic’s state will be changed back to normal I.e. powered.

harrisonjackson 6y ago
In that scenario, couldn't they just send an unmute command?
867-5309 6y ago
in the same vein, what about the overlooked 1mm x 1mm chip that holds logic such as {{ if red_led==active then pushAudio('udp://amazon.com/jeffsBathroomSpeaker') }}
- dmix 6y ago
  Considering the countless chips on most standard SoCs this is the correct answer. And presumably what the NSA does when they reroute your Dell or MacBook for an overnight session in a sealed off room at the post office. Doesn’t even need to be at Amazon’s factory in China of where ever. But that is largely feasible too. The difficulty is more about data exfiltration. Has to be appended to some real ‘normal’ request the next time a legitimate use of the mic is made, then piggybacks uploads on that connection. Recording all times when a voice is heard would also massively increase the payload sent to the server. If you were just passively network monitoring it could stick out. Which is not something nation states want. Forget these smart home mics, if I was a nation state I’d just stick with the mobile phones and laptops every person uses. People are already paranoid about their Alexas inherently (and far more likely to potentially care to look) making them a poor target for hacking. It’s far more useful to turn the thing they carry around with them 24/7 into an active microphone with GPS, and plenty of more exfiltration possibilities with any mobile and desktop OS network traffic.
- mlyle 6y ago
  Unless it has a microphone itself, that's difficult, because the actual microphone is depowered.
  - skzv 6y ago
    What does it mean for a microphone to be depowered? Doesn't the movement of the diaphragm induce a current, which is amplified- so it's the microphone amplifier that's depowered? Are we assured that the current produced by the diaphragm is too weak to reconstruct audio, even if it's very noisy?
    - mlyle 6y ago
      It's a MEMS microphone: silicon electromechanical device + amplifier in one package. First, this generally means that when depowered, the output signal line is connected to ground by the ESD protection path. Second, the actual mechanism which picks up the audio is generally variably capacitive-- a few picofarads-- in MEMS mics, and requires a pretty high bias (~15-200V) voltage to induce a usable signal for the in-package amplifier to be able to pick up the audio. To not only have the in-package amplifier turned off, but also no significant bias voltage across the microphone electrodes, and somehow pick this up on the other side of the trace would be somewhat miraculous.
      - skzv 6y ago
        Great, thanks for the detailed and informative explanation.
knaik94 6y ago
From using an echo at home, the unmuted state is only during the bootup process during which there's no processing or recording of audio going on anyway. If it shutdown muted mine starts up muted, even if the power cord is removed.
- mlyle 6y ago
  Is this the Echo Flex? The pictured schematic appears to disallow software re-muting. Otherwise, all this hardware protection is moot (mute? ;), because you can listen for a few seconds, and then turn the mute light back on. Or you can even toggle them back and forth really quick, and turn the light half on and keep the microphone's power pin capacitor charged.
- beervirus 6y ago
  > the unmuted state is only during the bootup process during which there's no processing or recording of audio going on anyway Is there any reason to believe that there's no processing or recording going on?
mlyle 6y ago
Yes, but at least this turns the light off and the light is stuck off (and can't be turned back on by software even if they decide to stop listening).
- aeternum 6y ago
  Sure but it's still a bad design. If the device ever loses power, or restarts for any reason while the mute is engaged an informed user must accept a non-zero probability that their privacy was invaded. I have wireless headphones that work like this and it's a terrible design. If they go out of range temporarily, they unmute. It makes the 'hardware' mute functionality absolutely useless since it cannot be relied upon to stay muted.
  - mlyle 6y ago
    Short of a switch that is sticky when powered off, or a design that comes up muted... or excessive wizardry to persist state, this is non-negotiable, though.
    - aeternum 6y ago
      Physical switches for mute are underrated, think of all the conference call time that could be saved (and embarrassing moments avoided) if laptops had physical mute switches.
    - ashtonkem 6y ago
      Slider switch solves this problem. They're well known for maintaining their state between reboots.
    - astura 6y ago
      >switch that is sticky when powered off This is a long solved problem, a lever switch. Laptops (usually enterprise laptops) sometimes have them to turn on/off wireless communication. https://ux.stackexchange.com/questions/34956/who-needs-an-external-on-off-wi-fi-button/34958 https://ux.stackexchange.com/questions/34956/who-needs-an-ex...
johnghanks 6y ago
Jesus - does everyone on this site live in a bunker using only candle light? Tip: you're insignificant and nobody at Amazon (or any company, for that matter) cares enough to spy on you.

by bobuk 6y ago

harrisonjackson 6y ago

In that scenario, couldn't they just send an unmute command?

867-5309 6y ago

in the same vein, what about the overlooked 1mm x 1mm chip that holds logic such as {{ if red_led==active then pushAudio('udp://amazon.com/jeffsBathroomSpeaker') }}

dmix 6y ago
Considering the countless chips on most standard SoCs this is the correct answer. And presumably what the NSA does when they reroute your Dell or MacBook for an overnight session in a sealed off room at the post office. Doesn’t even need to be at Amazon’s factory in China of where ever. But that is largely feasible too. The difficulty is more about data exfiltration. Has to be appended to some real ‘normal’ request the next time a legitimate use of the mic is made, then piggybacks uploads on that connection. Recording all times when a voice is heard would also massively increase the payload sent to the server. If you were just passively network monitoring it could stick out. Which is not something nation states want. Forget these smart home mics, if I was a nation state I’d just stick with the mobile phones and laptops every person uses. People are already paranoid about their Alexas inherently (and far more likely to potentially care to look) making them a poor target for hacking. It’s far more useful to turn the thing they carry around with them 24/7 into an active microphone with GPS, and plenty of more exfiltration possibilities with any mobile and desktop OS network traffic.
mlyle 6y ago
Unless it has a microphone itself, that's difficult, because the actual microphone is depowered.
- skzv 6y ago
  What does it mean for a microphone to be depowered? Doesn't the movement of the diaphragm induce a current, which is amplified- so it's the microphone amplifier that's depowered? Are we assured that the current produced by the diaphragm is too weak to reconstruct audio, even if it's very noisy?
  - mlyle 6y ago
    It's a MEMS microphone: silicon electromechanical device + amplifier in one package. First, this generally means that when depowered, the output signal line is connected to ground by the ESD protection path. Second, the actual mechanism which picks up the audio is generally variably capacitive-- a few picofarads-- in MEMS mics, and requires a pretty high bias (~15-200V) voltage to induce a usable signal for the in-package amplifier to be able to pick up the audio. To not only have the in-package amplifier turned off, but also no significant bias voltage across the microphone electrodes, and somehow pick this up on the other side of the trace would be somewhat miraculous.
    - skzv 6y ago
      Great, thanks for the detailed and informative explanation.

knaik94 6y ago

From using an echo at home, the unmuted state is only during the bootup process during which there's no processing or recording of audio going on anyway. If it shutdown muted mine starts up muted, even if the power cord is removed.

mlyle 6y ago
Is this the Echo Flex? The pictured schematic appears to disallow software re-muting. Otherwise, all this hardware protection is moot (mute? ;), because you can listen for a few seconds, and then turn the mute light back on. Or you can even toggle them back and forth really quick, and turn the light half on and keep the microphone's power pin capacitor charged.
beervirus 6y ago
> the unmuted state is only during the bootup process during which there's no processing or recording of audio going on anyway Is there any reason to believe that there's no processing or recording going on?

mlyle 6y ago

Yes, but at least this turns the light off and the light is stuck off (and can't be turned back on by software even if they decide to stop listening).

aeternum 6y ago
Sure but it's still a bad design. If the device ever loses power, or restarts for any reason while the mute is engaged an informed user must accept a non-zero probability that their privacy was invaded. I have wireless headphones that work like this and it's a terrible design. If they go out of range temporarily, they unmute. It makes the 'hardware' mute functionality absolutely useless since it cannot be relied upon to stay muted.
- mlyle 6y ago
  Short of a switch that is sticky when powered off, or a design that comes up muted... or excessive wizardry to persist state, this is non-negotiable, though.
  - aeternum 6y ago
    Physical switches for mute are underrated, think of all the conference call time that could be saved (and embarrassing moments avoided) if laptops had physical mute switches.
  - ashtonkem 6y ago
    Slider switch solves this problem. They're well known for maintaining their state between reboots.
  - astura 6y ago
    >switch that is sticky when powered off This is a long solved problem, a lever switch. Laptops (usually enterprise laptops) sometimes have them to turn on/off wireless communication. https://ux.stackexchange.com/questions/34956/who-needs-an-external-on-off-wi-fi-button/34958 https://ux.stackexchange.com/questions/34956/who-needs-an-ex...

johnghanks 6y ago

Jesus - does everyone on this site live in a bunker using only candle light? Tip: you're insignificant and nobody at Amazon (or any company, for that matter) cares enough to spy on you.