Air Gap

By: Claudio Buttice | Reviewed by John MeahCheckmark | Last updated: June 10, 2021

What Does Air Gap Mean?

An air gap is a security measure in which computers, computer systems or networks are not connected in any way to any other devices or networks. This is used in instances requiring airtight security without the risk of compromise or disaster. It ensures total isolation of a given system — electromagnetically, electronically and, most importantly, physically — from other networks, especially those that are not secure. In other words, data can only be transferred by connecting a physical device to it, such as a flash drive, external hard disk or DVD.

The term “air gap” is a merely metaphoric description of the conceptual gap required by the physical separation between the computers. Air-gapped networks and computers are used when maximum security of that system or the data stored in it must be ensured. Air gaps protect systems from malware, keyloggers, ransomware or other unwanted accesses. Typical examples include life-critical power plant controls, military and aviation computers, government networks, financial computer systems or computerized medical equipment, among others.

A lot of traditional electronic equipment like thermostats and home appliances have always been air-gapped due to their inherent limits rather than for security reasons. However, with the widespread diffusion of wireless components and “smart” devices, these products are no longer air-gapped, as they are connected to the internet.

Technically, even a simple desktop PC that is not connected to the internet could be considered an air-gapped system.

An air gap is also known as an air wall.


Techopedia Explains Air Gap

An air gap is maximum protection between a system and other devices/systems — apart from actually turning it off. Two disconnected systems or devices designate two security levels: low (unclassified) and high (classified). To move data, it often must be saved in some type of transportable medium. Moving data from low to high is simple, whereas moving classified data from high to low security requires a strict procedure prior to performing the transfer, due to the data’s classified nature.

Advantages of an Air Gap

  1. The air gap might prevent data destruction or leakage due to power fluctuations.
  2. The machine is protected from any malware that might be circulating the internet.
  3. The machine is secure.
  4. It's considered to be the most foolproof way of securing files and information from hackers, thieves, or spies due to the lack of connection in this type of system.

An air gap is one way to make it harder for hackers, thieves, or spies to access your files and generally control your computer system. It's important to note that just because a computer is not connected, it doesn't mean it's safe. There are still ways for hackers like viruses from USB devices that are plugged into the air-gapped machine or by Bluetooth connections from nearby devices other than Mobile phones.

The usual configuration of an air gap is a “sneakernet,” so-called because one must walk to the system and connect a method of data transfer. The idea is to make sure the only way to breach an air-gapped computer and compromise the system is to “cross the air gap.” This means having someone physically access the system themselves by sitting in front of it with a Wi-Fi dongle or USB device as it is otherwise inaccessible.

A system or device may require certain security precautions, such as:

  • Entirely banning local wireless communications

  • Preventing electromagnetic (EM) leakage by placing the system/device in a Faraday cage to block wireless transmissions

  • Protecting the system from other types of attack, such as optical, thermal or acoustic

Despite the high level of security produced by an air gap, some advanced techniques have been ideated to find a way to breach air-gapped computers, although some of them are still more theoretical than practical. Cutting-edge acoustic channels employing ultrasonic, inaudible sound waves can be used as an attack vector against hackable smartphones that are capable of picking up higher frequencies. Data can also be siphoned through radio signals even when Bluetooth is disabled. That is why, in many high-security environments, mobile phones are not allowed in range of the most critical systems.

Surveillance cameras can also be hacked, as they allow optical transmission of data through their LEDs. Thermal hacks can also be used, but the bandwidth is very low, so they are far from representing a practical threat at the moment.



Air Wall, Air-Gapping

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