What is an Air Gapped Computer?
1 Star2 Stars3 Stars4 Stars5 Stars (No Ratings Yet)

What is an Air Gapped Computer?

Everything you need to know about air gapped systems and their security

If you follow cyber security for long enough you’re bound to come across the term “air gapped computer.” As it relates to computer networking, air gapping is a security measure to ensure that a computer network is physically isolated from unsecured networks like the internet and local area networks.

The name derives from the conceptual air gap that should exist with physical separation.

What is an air gapped computer?

An air-gapped computer is isolated from unsecured networks, meaning that it is not directly connected to the internet, nor is it connected to any other system that is connected to the internet. A true air gapped computer is also physically isolated, meaning data can only be passed to it physically (via USB, removable media or a firewire with another machine).

Some companies will market that a network or computer is air gapped despite the fact that the systems are only separated with a software firewall. Be cautious of this, firewalls can be breached as a result of both security failures and mis-configurations.

A true air gapped computer is physically isolated.

Here’s a good example from pop culture. Do you remember the scene from the movie Mission Impossible where Tom Cruise rappels down from the ceiling?

what is an air gapped computer?

It’s one of the most famous scenes in movie history. In it, Cruise lowers himself from an air vent and dangles just feet above the floor as he steals a list from a computer in FBI headquarters.

That is an air gapped computer.

Who uses air gapped computers/networks?

You will tend to find air gapped computers implemented in high security environments, think classified military networks and payment networks. Here are some more examples of networks or systems that might be air gapped:

  • Military computer systems and networks
  • Government computer systems and networks
  • Financial computer systems and networks
  • Industrial control systems:
    • SCADA
  • Life-critical systems:
    • Nuclear power plants
    • Aviation Computers:
      • FADECs
      • Avionics
    • Medical Equipment

Interestingly, as more and more devices come online and become “smart,” a number of products that have traditionally been air gapped like thermostats, electronic sprinklers and automobile components are now connecting to the public internet.

Are air gapped computers completely secure?

No. At least not from Tom Cruise. Seriously though, while you definitely don’t need to freak out and go find an alternative to air gapping, it would be silly to pretend that nothing can go wrong. Air gapped computers can still be breached. Granted, it’s a hell of a lot harder to do when a computer is air gapped, but methods exist.

The easy way to breach an air gapped computer

Good old fashioned social engineering. That’s right, the easiest way to breach an air gapped computer is to find a human intermediary to wittingly (or possibly unwittingly) breach the computer. To do this they will need to access the computer themselves and attach a USB device like a flash drive or a Wi-Fi dongle.

That’s the easy way.

Other ways to breach air gapped computers

If you want to get a bit more scientific, there are other way channels to extract data from an air gapped computer, they include:

  • Electromagnetic
  • Acoustic
  • Thermal
  • Optical


Electromagnetic channels are the oldest attack vector of the group. These techniques include eavesdropping on EM radiation from the computer’s memory bus and monitoring leakage from USB ports and cables. Because electromagnetic channels have been widely studied, EM shielding has become a fairly common defensive measure.


Recently, acoustic channels have become a popular attack vector on account of the proliferation of hackable smartphones that are capable of picking up audio signals that the human ear can’t differentiate from background noise. The most cutting-edge area involves the use of ultrasonic sound waves with higher frequencies that are both inaudible and provide greater bandwidth.


Unlike the other categories, thermal hacks are more theoretical than anything at this point. While they have been demonstrated, the bandwidth is low, measuring in the low tens of bits per second over a very short distance. It’s unclear whether this will ever become a practical attack vector.

Optical Transmission

The most recent channel to be explored, optical transmission is bolstered by the advent and widespread availability of easily-hacked surveillance cameras. The cameras include LEDs on almost every system and can transmit substantial amounts of information.

How difficult is it to breach an air gapped computer?

It’s extremely challenging. The common theme with all of these attacks is that they require physical proximity. We’re talking about being close enough to record Electromagnetic radiation, pick up inaudible sound waves or rappel down from the ceiling.

Beyond that, most of what I’ve just described are proof-of-concept attacks. That means they’re all:

  • Difficult to execute
  • Contingent upon numerous conditions being met
  • Developed by security researchers… for research purposes

That last point is especially salient. These exploits were pulled off primarily to raise awareness, they’re not things you are likely to find in the wild. On the flip-side, most cybercriminals don’t provide proofs of concept, so there could be other methods we don’t even know about.

Regardless, the best, most reliable method continues to be social engineering.

Six tips for better securing air gapped computers

As we’ve covered, just having a computer air gapped doesn’t provide quite the level of security as it used to. Again, that’s not to say that air gapping isn’t still a phenomenal security mechanism. It is. But could you do more to make your air gapped systems safer?


Here are six tips for air gap security:

  1. Secure the machine off-site or in a fully-secured room
  2. Make sure all cables to the machine are properly shielded
  3. Use USB Port Blockers to plug any unused USB ports
  4. Turn the machine off and unplug it from the power source when not in use
  5. Replace all standard drives with SSD
  6. Encrypt all data
  • “Air gapped” and “stand alone” are NOT the same thing. A stand-alone system is not necessarily air-gapped, and vice-versa. A stand-alone system is one that can perform its functions without the use of other devices; that doesn’t mean it isn’t connected to other devices, just that it doesn’t need to be.

  • Good article. What do you think of what these guys are doing? Not sure I get it entirely, but it seems to be saying they have an underground data center with an air gap system which can be put on/offline from a remote location for occasional access. I guess like an air gap that is closed when you want to use it. How they do it is unclear. https://www.youtube.com/watch?v=xUYrmFtVrrY Think that’s safe?

  • Secure KVMs, which maintain the air gap, are used throughout security organisations, to keep the desks tidy..

  • I use a Chrome computer to go on-line, but my win10 msi based computer stays offline. I only use win10 because Xp has been made obsolete by the thrice cursed microsoft (chicom). This causes some problems but workarounds exist. Need ideas about downloading programs that help finish and refine Speech Recog and Command functions without connecting to MS. THANK YOU

  • Not for nothing, but Cruise’s character was stealing a NOC List from CIA Headquarters @ Langley. Not FBI. Just saying… 🙂

  • I don’t understand why this is so novel. Any mission critical computer system should be “air gapped.” you want to read my water meter? Get your ass into a truck, drive up with a hard hat a clip board, and snacks for my dog

  • Air gapped has to deal with a hydronic pressurized system and an open space in a pipe(several inches) that could feed that system. The space is wide enough that no bacteria can cross to the area determined to be clean and sanitary.

Leave a Reply

Your email address will not be published. We will only use your email address to respond to your comment and/or notify you of responses. Required fields are marked *

Captcha *


Patrick Nohe

Patrick started his career as a beat reporter and columnist for the Miami Herald before moving into the cybersecurity industry a few years ago. Patrick covers encryption, hashing, browser UI/UX and general cyber security in a way that’s relatable for everyone.