What is an Air Gap and How Does it Protect Your Data?

Have you ever wondered why Tom Cruise had to break into CIA headquarters to steal data from a computer in the original Mission Impossible movie? Couldn’t he have just hacked in over the Internet? Well, no… in the movie, at least, that critical CIA database was “air-gapped.” It was physically separated from a network that Cruise's character could breach. Great cinema ensued as a result.

Air gaps used to be quite common. Today, the reverse is true. Nearly all computers are connected to networks and, from there, to the outside world. However, the increasingly dangerous cyber threat environment makes it wise for certain industries to maintain air gaps as part of a cyber resilience strategy. This article discusses the air gap and how it protects data.

Understanding air gaps in data security

Air gaps enhance cybersecurity measures; let's explore the basics of what they are and how they work.

What is an air gap?

As its name suggests, an air gap creates a physical separation between a digital resource and any external connection. If a user on the network wants to access the resource, they meet “air.”

The term can refer to entire networks disconnected from the outside world, such as those found on ships at sea (assuming no satellite internet link). Individual resources like servers and storage arrays can be air-gapped if they run without any connections to a network or the Internet. A cave storing backup tapes is also an air-gapped environment. An air gap might also include segmented networks and disconnected equipment located in the same data center as hardware accessible to the Internet.

The evolution of air gaps in cybersecurity

Initially, computer users had no alternative but to deal with an air gap. If you wanted to use the computer, you brought your stack of punch cards into the “glass house,” as the air-conditioned rooms hosting mainframes were called, and fed them into the machine. Computer networking evolved with the introduction of “point-to-point” connections using phone lines, so systems remained air-gapped when disconnected.

Such separation was a preference for organizations that valued data security and privacy. Military and intelligence facilities ran air-gapped systems as a matter of policy. Air gaps have evolved as technology and cyber threats have become more sophisticated and complex. For example, the air-gap network switch creates a physical separation between two networks, even if they are in the same building.

Air gaps remain relevant, even essential, in this era of cloud computing and hyper-connected systems. Connectivity and cloud platforms are great for digitalization and productivity, but potentially bad for security. With threats able to breach sensitive cloud systems and cloud storage, a logically air-gapped cloud backup volume offers a measure of protection. A logical air gap uses cryptography to create the virtual equivalent of a physical air gap.

The benefits of using air gaps

Air gaps offer several benefits to organizations that use them. They’re an effective last line of defense, for one thing. If other countermeasures fail, having systems or data walled off and inaccessible helps preserve data privacy and integrity. This safeguard makes air gaps a key component of a multi-layered security strategy. Multi-layered security involves protecting digital assets using more than one countermeasure, such as perimeters, endpoint security, network security, and so forth. Air gaps stand in the way of attackers if they make it past these other layers.

This multi-layered approach is a compelling advantage for sensitive government or corporate data. If ransomware attackers cannot reach air-gapped data, for example, they can’t encrypt and hold it for ransom. An air-gapped organization that experiences a ransomware attack can restore its systems using that air-gapped data. This method is one way air gaps support cyber resilience.

How an air gap works to protect data

Air gaps protect data by isolating it. For example, storing tape backups in an offsite facility is an extreme cyber resilience solution. No one can reach that backed-up data over a network. However it’s implemented, the air gap can mitigate the risks of remote hacking, ransomware, and malware from spreading. This is partly because hackers tend to move laterally across networks after they gain access. They discover sensitive systems and data as they move. An air-gapped system may be impossible for the hacker to discover. Or, if discovered, the air gap makes it impossible for the hacker to breach it.

Challenges and limitations of air gapping

Air gaps have their share of challenges and limitations. They can be difficult to deploy and cumbersome to maintain, which can compromise the security benefits of the air gapping process.

• True air gaps are hard to realize: Many modern computer systems have connections to the Internet or corporate networks that administrators don’t know about. In some cases, the culprit is a wireless device that’s plugged into the air-gapped system. Without anyone realizing it, a network-connected device can provide a pathway through the air gap. Automated device discovery tools often reveal the existence of such backdoors.

• Air gaps have physical vulnerabilities: Air-gapped systems usually have physical ways to connect to devices, such as swappable hard-disk drives or USB ports, making them vulnerable to human error and enterprising attackers, including insiders. A malicious actor can gain unauthorized access to an air-gapped environment using such a method and proceed to delete, modify, or exfiltrate data.

• Supporting an air-gapped environment can be a struggle: Servers and storage equipment in an air-gapped environment need updates and other maintenance that requires external access. Installing a software upgrade on an air-gapped server, for instance, means that someone has to connect to that server, either physically or over a temporary network connection. This process creates risk exposure. Alternatively, the difficulty in providing support leads the air-gapped system to run out-of-date or insecure software.

What can be done to mitigate these risks? One solution is to use logical air gaps that don’t have to be physically separated. Wasabi provides this capability with immutable backups, which is part of our standard cloud object storage offering. The backed-up data is encrypted, so it cannot be breached. Nor can it be modified or deleted, rendering it impervious to ransomware attacks.

A data diode is an alternative approach that uses a hardware device that allows data to flow only in one direction. It’s like a one-way valve that prevents an attacker from accessing or exfiltrating data.

Conclusion

Air gaps can be a useful security countermeasure and an essential element of a cyber resilience strategy. By physically isolating data and systems from network connections, air gaps make it impossible for malicious actors to cause disruption or breach sensitive data. Logical air gaps use cryptography and network segmentation to create the same kind of separation in devices that remain connected to networks. Backed-up data in air-gapped environments remains untouched during a major cyber incident, such as a ransomware attack.

We are serious about security and data resilience. Store your data with us and we can help you quickly and affordably bounce back from cybersecurity incidents or accidental data loss.