Mic drop: How to keep snoops from listening to your laptop’s microphone – Macworld

It’s the infosec (information security) shot seen round the world. Mark Zuckerberg posted an Instagram photo celebrating 500 million monthly users, and his Mac laptop was visible in the background. As Chris Olson pointed out on Twitter, Zuckerberg had put tape over his laptop’s camera and over its microphone input (not a mic jack).

This sparked an interesting and useful discussion that built upon an earlier bit of virality, when Edward Snowden, the man who exposed the NSA’s data-gathering behavior, showed on a Vice program on HBO how to disable audio and video inputs on a smartphone by removing them.

That may seem extreme. It is. Few of us are scrutinized, tracked, or hacked at the scale of Mark Zuckerberg or Edward Snowden. But we shouldn’t be sanguine. While OS X vulnerabilities haven’t led to widespread exploitation (so far), attackers and government agencies have been able to insinuate themselves into Macs.

Some people also aren’t worried so much about the actuality of being a target, but want to prevent the potential of being one on general principle. A camera is easy to block, because you can effectively black it out. A microphone is harder. Covering it may muffle the volume, but because of how they’re placed in Apple’s laptops, some sound would bleed through. Since Zuckerberg’s savvy, the tape may be a reminder that he made a deeper change to software or hardware.

For most people, the fear with mics being tapped isn’t that your conversation would be listened into because you have some particular secret. But rather it’s that you could simply be the random subject of probing. There’s also the very realistic potential that NSA-scale audio-to-text extraction moves with the inevitable decrease in cost for computational power into something criminal syndicates find useful. Mass snarfed audio could be scanned for context—such as you reading a credit-card number aloud or discussing a confidential business matter. Anything technically plausible today but infeasible due to scale will eventually become practical.

So if you don’t want your microphone to be active and a piece of tape isn’t enough, what steps can you take? I asked security and hardware experts, and there’s a graduated path you can walk down.

Set microphone input to zero

You can start with a graphical user interface, and open the Sound system preference pane. For each device listed in the Input tab, set the Input Volume to zero (drag all the way to the left). This prevents gross misuse by software that might otherwise be able to use an audio source without you realizing it, as the input volume should be controlled through this approach.

privatei sound pref pane mic

Set audio input to zero for all your mics.

Malicious software may be able to reset input volume, bypassing these settings, or pull audio directly from a device at a stage before this setting may be applied. However, it’s the simplest and most direct change you can make that has no other repercussions. Turn input volume up for a given device whenever you need to, and unplug any USB input devices while you’re not using them for extra protection.


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