Not all conferencing software does this reliably

from Benjamin Grundken
Muting or “muting” the microphone doesn’t actually turn off the microphone in all video conferencing programs, according to one study. Although it was not possible to hear the spoken word of a program despite the shutdown, the approximate user activity could be determined.

Video conferencing software was indispensable during the corona pandemic. Today, US researchers from Loyola University Chicago and the University of Wisconsin-Madison put various data protection programs to the test. These included the Enterprise version of Zoom, Slack, Teams, Skype and Cisco Webex.

In the context of Webex, the researchers found that, despite the mute function being activated, the program polled the microphone in such a way that current activity could be determined with a high degree of probability. Specifically, not all words were recorded, but a kind of volume level of background activity was recorded. The software transmitted this audio telemetry data to the Cisco servers approximately once per minute.

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The researchers, or more specifically a tool they programmed, were able to use this data to determine with an 82% success rate what activity was going on in the room with what device – for example, whether cooking was in progress or if the person typed on the keyboard. Cisco has now stopped sending telemetry data after the results were known. According to the company, there is no security hole, but a notification function on mute behind the data request.

Basically, the researchers complain in their study that video and audio signals are handled inconsistently. Anyone who communicates via program versions for browsers, for example, is on the safe side, because WebRTC is used for real-time communication and the microphone is disabled according to the rules. It is also true that in Windows and MacOS turning off the camera is regulated at the operating system level and this is also well implemented. However, disabling apps depends on how the respective developers implement it. It is also rarely clear whether the microphone is picking up sound.

Source: Heise, Communication from researchers

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