What is the principle behind Defense-in-Depth in security?

The principle behind Defense-in-Depth is centered on the idea of implementing multiple levels of protection to safeguard information systems. This approach recognizes that no single security measure is foolproof, and by layering different security controls, organizations can create a more robust defense against a variety of threats.

By employing various protective measures, such as firewalls, intrusion detection systems, encryption, and access controls, any vulnerabilities in one layer can be mitigated by the strength of the others. This multi-faceted strategy not only complicates the attacker's ability to penetrate defenses but also provides a fallback mechanism. If an attacker bypasses one layer, they will encounter additional barriers, thus increasing the chances that the breach can be detected and contained.

This method contrasts with relying solely on a single level of security, which can lead to critical weaknesses if that single layer fails. Additionally, while perimeter defenses and user access rights are important aspects of cybersecurity, they are only parts of a comprehensive Defense-in-Depth strategy rather than its core principle.