The three principles
Zero Trust replaces perimeter-based security ('inside the firewall is trusted') with three working principles: verify explicitly (every access request authenticated and authorised based on all available signals — identity, location, device, application, data sensitivity), use least-privilege access (just-in-time, just-enough, risk-based adaptive policies), and assume breach (segment to limit blast radius, end-to-end encryption, continuous improvement through analytics).
How Microsoft 365 implements it
Microsoft 365 ships the building blocks: Entra Conditional Access for verify-explicitly, Entra PIM for least-privilege, Defender XDR + Sentinel for assume-breach detection, Microsoft Purview for data segmentation. Implementing Zero Trust isn't buying a product — it's configuring policies across these features. Frontrow's Zero Trust deployments typically take 8–12 weeks across an Australian midmarket tenant.