An Air Gap, or network isolation, is a physical or logical security mechanism that isolates an IT system or a set of backups from any remote network, including the Internet and the corporate local network. This principle eliminates any direct digital communication path with the outside world, providing maximum protection against unauthorized access and data compromise. An Air Gap can serve various purposes: making backups immune to cyberattacks, preserving the integrity of critical information or ensuring business continuity in the event of a major incident.

How an Air Gap works

When an Air Gap is in place, it prevents any remote attack vector from reaching the protected system. In a conventional infrastructure, malware often infiltrates through spyware or a backdoor and then spreads laterally across the network. By removing connectivity or locking down write flows, the Air Gap breaks this chain of infection. Data is transferred to the isolated zone either manually (swapping physical media) or through sealed logical mechanisms that automatically close the communication channel as soon as the backup has run.

Types of Air Gap

Air Gaps can take different forms, depending on how they are implemented and used:

  • Physical Air Gap: A complete hardware disconnection. Data is written to removable media (magnetic tapes, cartridges, external hard drives) that are physically unplugged and stored offline in a secure location.
  • Logical (or virtual) Air Gap: Software-based isolation relying on sealed networks and immutability technologies. Although a physical link exists to send data streams, the target system rejects any modification, deletion or remote access command once the transfer is complete.
  • Cloud Air Gap: Storage located outside the corporate network with a trusted third party, combining end-to-end encryption, strict flow restrictions and fully sealed access policies.

Impact and challenges of an Air Gap

Implementing an Air Gap has a direct impact on the resilience of an information system against cyberthreats:

  • Protection against ransomware: Ransomware generally seeks to cripple or destroy connected backups before encrypting the infrastructure. Air-gapped storage remains out of reach and guarantees the ability to restore.
  • Neutralizing leak-based extortion: When facing doxware, which combines encryption with the threat of disclosing confidential data, having clean air-gapped backups makes it possible to restore services immediately and reduces the impact of the extortion.
  • Immunity to network attacks: Interception attempts such as man-in-the-middle attacks, or server overloads caused by a denial-of-service attack (DDoS), are ineffective against a system that is physically or logically disconnected from the network.
  • Protection against targeted hacking: Even if cybercriminals manage to compromise highly privileged credentials through a whaling attack targeting senior management, they cannot alter backups isolated from the administration network.

Prevention and protection

To ensure the effectiveness of an Air Gap strategy, it is essential to implement rigorous security measures:

  • Adopting a Zero Trust architecture: Applying the zero trust model ensures that no access to storage areas is granted by default, requiring explicit and systematic verification of every request.
  • Applying the 3-2-1-1-0 rule: Keep 3 copies of your data on 2 different media, including 1 offsite, 1 offline or immutable copy (Air Gap) and 0 errors during restore tests.
  • Regular audits and restore tests: Conducting penetration tests and disaster recovery drills makes it possible to verify that isolated data is usable and free from any corruption.
  • Strict access control: Restricting access privileges and enforcing multi-factor authentication (MFA) limits the risk of compromise on backup management interfaces.

Conclusion

An Air Gap is a fundamental protection measure for ensuring the resilience of IT systems against advanced cyberattacks. By hermetically isolating critical data, this method prevents attackers from permanently crippling an organization's operations. Ensuring the security of your business requires constant vigilance and the integration of disconnected or unalterable backups at the core of your IT strategy.

Make sure you invest in robust backup solutions, such as those offered by KiwiBackup, to protect your data and ensure the availability of your services against potential threats such as the loss or encryption of your backups.