Please excuse the terminology as I'm no expert in information security. My question is pretty straightforward:

How can I guarantee* that I am the only one with access to my local machine's data (screen, microphone, camera, files)?

* With the assumption that no one will physically come into my apartment and mess with the hardware.

I own a Macbook Pro running macOS. I have heard of cases where a laptop's data (camera/microphone etc..) has been accessed remotely without consent. I wonder whether it is possible to absolutely prevent such attacks.

Up to recently I thought that the hard drive's content was safe, but I don't think so anymore.

The simplest procedure I came up with is turning off the WiFi, reading/writing data to an external drive (like a thumb drive), unplugging the drive (and turning the WiFi back on).

Does the method above guarantee that no one beside me can access the external drive's data? Are there any easier methods?


  • It's not possible. If there's a program that can access it, then there can be a program that both accesses it and relays information from it across the network (or a program that sends that data to another program that relays it across the network).
    – user
    Commented Oct 16, 2019 at 12:27

2 Answers 2


There is no way to have both internet connectivity and foolproof security. Security is implemented through multiple layers of defenses. Each layer is designed to mitigate exposure and risk of information leaks. The more layers of security that are implemented, the less usable the system becomes. The remaining risk, which is always present, is called residual risk. A determination is then made if this residual risk is acceptable, at which time it becomes accepted risk. This is a very basic description of information security.

The only way to be sure information will not leak is to never put the information on the device in the first place and therefore the system is completely unusable.

You are not clear on your use case, and if network connectivity of any kind is actually necessary. But, the most secure configuration that doesn't make the system completely unusable and is still reasonable for most home users is:

  • Air gap the machine. Absolutely no network connectivity. All data exchanged with the system is done by physically walking up to the device and copying it from one device to another.
  • Strong, full disk encryption. Make sure all data stored on physical media is securely encrypted with a modern encryption algorithm that uses a long, hard to guess, key.
  • Keep the machine powered off and/or in a locked and encrypted state when not in use.

Note, there are still plenty of ways this system can be compromised. Just read about the Stuxnet malware which was able to penetrate several security layers of a highly secure Iranian nuclear facility. The question is if you want to protect your information from script kiddies and every day hackers, or if you want to protect your information from the CIA or Israeli Mossad.


If you want a 100% guarantee that no-one accesses the files on your Macbook, then I'm sorry. The only way to get real certainty is a stand-alone machine specially for this purpose. As you seem to have been connected to wifi and wish to reconnect, it will never be 100% safe.

If you go a step further:

  • disconnect the macbook from the networks (Wifi, cabled etc.)
  • re-install the OS
  • connect the drive and access the external drive

You still have the same BIOS where you boot from. See https://www.schneier.com/blog/archives/2013/11/badbios.html on a possible attack here.

If you do not re-install the OS, anything that you may have picked-up could access your drive, make copies etc.

The way to look at it is to do a risk analysis. Basically, you ask your self, how bad would it be if someone accesses these files, what are the chances that someone access the files and what are you willing to do about it.

Disconnecting Wifi certainly reduces the chance that someone else accesses the files. But there is a chance that someone has installed a defered copy tool, so the miscreant can pick up the files later. Then there are some basic hygiene measures, that you must have heard before:

  • don't let anyone else use your computer
  • only install software from a trusted source
  • do not visit ill-reputed websites
  • boot from time to time
  • keep OS and software up-to-date (at least install security patches)
  • do not run any servers on the system (ssh, webserver, or * gasp * telnet)

That will reduce the chance that someone can install any delayed access software on your system.

Anything but the stand-alone solution will increase the chance.

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