What does the principle of defense in depth entail?

The principle of defense in depth involves the implementation of multiple layers of security controls to protect an information system. This strategy recognizes that no single security mechanism is foolproof and that relying solely on one type of defense can leave systems vulnerable. By employing various overlapping layers of security—such as physical, technical, administrative, and operational controls—organizations can create a more resilient security posture.

If one layer is breached, subsequent layers serve as backups, helping to deter or delay an attacker from gaining unrestricted access to sensitive systems or data. This approach not only increases the overall security but also provides a more comprehensive solution to address the multifaceted nature of security threats in an ever-evolving landscape.