You’re muted – or are you? Videoconferencing apps may listen when mic is off • Hacker News Board

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#81

Post by georgyo » Wed, Apr 13, 2022, 6:16 PM UTC

Sakos wrote: post #68

SkyPuncher wrote: post #10

I feel like they're trying to make an insidious suggestion about the usage of these. IMO, there's likely a good reason - user experience. At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a sof…

Honestly, it feels like most people here aren't reading the article. > The researchers then decided to see if they could use data collected on mute from that app to infer the types of activities taking place in the background. Using machine learning algorithms, they trained an activity classifier using audio from YouTube videos representing six common background activities, including cooking and eating, playing music…

I think there are two different problem here.

1. When the mic is soft muted, information is getting sent to the conference provider which could leak information about private matters.

2. When the mic is not muted all information is definitely going to the conference provider in a way they can decrypt so they can mix it.

That is to say that when using most conference software, you have already granted then access to contents of the meeting.

If you can't trust them to not miss use information they get when the mic is off, then you also can't trust them when the mic is on.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#82

Post by macintux » Wed, Apr 13, 2022, 6:16 PM UTC

SkyPuncher wrote: post #10

I feel like they're trying to make an insidious suggestion about the usage of these. IMO, there's likely a good reason - user experience. At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a sof…

> With that being said, if you really care about privacy, consider getting a hardware mute microphone.

But still consider using both software and hardware mutes. I was on a sales call years ago and activated the hardware mute. While one of our salespeople was talking I groaned out loud, and the call suddenly went silent. Somehow the hardware mute had failed, despite the light being lit.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#83

Post by zelphirkalt » Wed, Apr 13, 2022, 6:18 PM UTC

SkyPuncher wrote: post #10

I feel like they're trying to make an insidious suggestion about the usage of these. IMO, there's likely a good reason - user experience. At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a sof…

> At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a software level. This way the mic is always hot and ready to relay audio as fast as the software can switch.

Another solution is to mute at the microphone, if your hardware has a button for that. This way the application can do whatever it wants, it will still get nothing. Using the hardware button is often less effort, than switching windows, finding that unmute button visually and moving the mouse to that button to click it. Or one could use push to talk. Since there are ways to mute yourself without having to do it in the app, it would be acceptable, if unmuting took a part of a second to be effective, indicating that by some "unmuting ..." label somewhere.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#84

Post by dundarious » Wed, Apr 13, 2022, 6:20 PM UTC

The actual study appears to be here: https://wiscprivacy.com/publication/vca_mute/

The findings are largely reassuring, to be honest:

> 1. Continuously sampling audio from the microphone: apps stream data from the microphone in the same way as they would if they were not muted. Webex is the only VCA that continuously samples the microphone while the user is muted. In this mode, the microphone status indicator from an operating system remains continuously illuminated.

> 2. Audio data stream is accessible but not accessed: apps have permissions to sample the microphone and read data; but instead of reading raw bytes they only check the microphone’s status flags: silent, data discontinuity, and timestamp error. We assume that the VCAs, like Zoom, are primarily interested in the silent flag to tell if a user is talking while the software mute is active. In this mode, apps do not read a continuous real-time stream of data in the same way as they would while unmuted. Most Windows and macOS native apps can check if a users is talking even while muted but do not continuously sample audio in the same way as they would while unmuted. In this mode, the microphone status indicator in Windows and macOS remains continuously illuminated, reporting that the app has access to the microphone. We found that applications in this state do not show any evidence of raw audio data being accessed through the API.

> 3. Software mute: apps instruct the microphone driver to completely cut off microphone data. All of the web-based apps we studied used the browser’s software mute feature. In this mode, the microphone status indicator in the browser goes away when the app is muted, indicating that the app is not accessing the microphone.

> The notable exceptions to these trends are the Microsoft VCAs (Teams and Skype) and Cisco Webex. Microsoft VCAs are much more difficult to trace because they do not use the standard Windows userland API. Instead, they directly make calls to the operating system. Since the Windows syscall interface is undocumented, we could not determine how Teams and Skype use microphone data when muted. More interestingly, we observe that Cisco Webex — unlike the rest of the Windows native VCAs — continuously accesses the microphone while muted.

I still unplug my desktop's external camera and microphone when not in use (9" outty-inny cables plugged into my monitor so those ports are accessible), and use hardware buttons (that may really be implemented in software, unfortunately) to mute during calls, and can just flick the camera to point at the ceiling. Will be more of a concern when I'm back to laptop living.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#85

Post by nemothekid » Wed, Apr 13, 2022, 6:20 PM UTC

Sakos wrote: post #68

SkyPuncher wrote: post #10

I feel like they're trying to make an insidious suggestion about the usage of these. IMO, there's likely a good reason - user experience. At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a sof…

Honestly, it feels like most people here aren't reading the article. > The researchers then decided to see if they could use data collected on mute from that app to infer the types of activities taking place in the background. Using machine learning algorithms, they trained an activity classifier using audio from YouTube videos representing six common background activities, including cooking and eating, playing music…

Because a video conferencing app with a bad UX is going to be quickly supplanted with one with a better UX; the privacy concerns of being spied on by a video conferencing app while you are muted is very minute for most people.

There should be a line between "companies doing whatever they want" because of some implied "nefarious" reasons, and "companies doing whatever they want" because their customers want a better experience even if it has security/privacy implications.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#86

Post by zelphirkalt » Wed, Apr 13, 2022, 6:21 PM UTC

prettyStandard wrote: post #41

Freak_NL wrote: post #24

Earlier quoted context omitted.

I hate the latter, because I use a keyboard shortcut to mute/unmute the microphone on the OS-level. This works fine with Google Meet, but in Microsoft Teams I have to use the button in its UI because that pop-up gets in the way (also: Teams not working at all in Firefox, what's up with that?).

It's BS. I changed my user agent to Chrome and it worked just fine.

It is BS, but when I tried that, I had other things not working, like sharing my screen. So it is BS, but not merely for looking at the user agent of the browser, but for the software development incapability or unwillingness on the side of MS. (Edit: While basically every other voice chat / video chat web app works fine on FF, so basically everyone but MS and Slack has solved this problem years ago. Go figure.)

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#87

Post by systemvoltage » Wed, Apr 13, 2022, 6:22 PM UTC

subpixel wrote: post #76

systemvoltage wrote: post #25

Earlier quoted context omitted.

Once I was on Teams meeting and someone exclaimed “We can see your screen, systemvoltage!”. Sure as hell, I wasn’t sharing anything. Thankfully I wasn’t browsing HN, but writing code. These things implemented somewhere in the middle of the stack seems dangerous. I much more prefer a slider switch. Preferably made from real atoms and molecules.

Not long ago I dialed into a 100+ person, 3+ hour long quarterly planning type call. It was a video call, but I had to be in the car for part of the time so I dialed in. After sitting through over an hour, including the part I thought was essential to my team, I jumped off the call and proceeded to explain the shit show to my fellow passengers for 15m or so. When I got to my destination and pulled out my phone I disc…

Yes, be careful. You were lucky. Also, bloated apps lie to you and UIs are buggy, what you see in the UI may not be the case.

I now disabled screensharing in MacOS privacy settings for all apps unless I am explicitly sharing.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#88

Post by UncleMeat » Wed, Apr 13, 2022, 6:22 PM UTC

Sakos wrote: post #68

SkyPuncher wrote: post #10

I feel like they're trying to make an insidious suggestion about the usage of these. IMO, there's likely a good reason - user experience. At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a sof…

Honestly, it feels like most people here aren't reading the article. > The researchers then decided to see if they could use data collected on mute from that app to infer the types of activities taking place in the background. Using machine learning algorithms, they trained an activity classifier using audio from YouTube videos representing six common background activities, including cooking and eating, playing music…

If your VC software decides to perform signal processing on the microphone input while it is running but you are muted then yes, it can determine things about your behavior.

But that's true for literally all applications running on your computer. Evil software running on your machine can do all sorts of bad things.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#89

Post by UncleMeat » Wed, Apr 13, 2022, 6:23 PM UTC

cortesoft wrote: post #79

Godel_unicode wrote: post #18

Earlier quoted context omitted.

Teams has a notice that it pops up if you're talking and on mute, and there's another for if you're not on mute but your mic is producing no signal (mic has it's own mute). I find those super helpful, personally.

Yeah, Meet does the same thing. I find it annoying, because I am muted because the kids are making a bunch of noise, not because I am trying to talk. I am muting because I don't want the sound in my room broadcasted... if it was silent, I wouldn't have to mute!

In like 25% of my meetings, somebody is accidentally muted while they are trying to speak. The popup speeds up the process of them unmuting.

Re: You’re muted – or are you? Videoconferencing apps may listen when mic is off

#90

Post by phendrenad2 » Wed, Apr 13, 2022, 6:24 PM UTC

Sakos wrote: post #68

SkyPuncher wrote: post #10

I feel like they're trying to make an insidious suggestion about the usage of these. IMO, there's likely a good reason - user experience. At a hardware level, grabbing the microphone can take time. Even worse that timing is inconsistent across devices, workloads, etc. That leads to a bad experience when unmuting and needing to delay your commentary. The solution to this is to keep the microphone on, but mute at a sof…

Honestly, it feels like most people here aren't reading the article. > The researchers then decided to see if they could use data collected on mute from that app to infer the types of activities taking place in the background. Using machine learning algorithms, they trained an activity classifier using audio from YouTube videos representing six common background activities, including cooking and eating, playing music…

Why did you move the goalpost? The comment you're responding to claims that there isn't a malicious purpose here. You instead claim to rebut it by saying that it's "concerning for those concerned with privacy". Can you see how those are different things?