Defense in Depth

Defense in depth is a security strategy that layers multiple defensive mechanisms so that if one control fails, others remain to prevent or limit the impact of an attack. It originated from military strategy and applies to cybersecurity by combining preventive (firewalls, WAFs), detective (SIEM, IDS), and responsive (incident response) controls. No single security control is 100% reliable, so redundancy at each layer is essential. Defense in depth is a core principle of NIST and ISO 27001 frameworks.

Why it matters for your website

• 1Foundational principle in modern security — harder to retrofit than to build in from the start
• 2Reduces breach impact by limiting what attackers can access if they get in
• 3Required control in ISO 27001, NIST CSF, and most compliance frameworks