Zero Trust is one of the most used — and most misunderstood — terms in enterprise cybersecurity. Most SMEs hear it and think it's something for large enterprises with six-figure budgets. It isn't. Zero Trust is a design principle that can be implemented incrementally, on the infrastructure you already have.
What Zero Trust actually means
The traditional security model is based on the perimeter: "inside" is trusted, "outside" is not. Zero Trust starts from a different premise: trust no one by default, always verify. Every access attempt is verified based on context: who you are, where you're accessing from, with what device, and what you want to do.
The three pillars of Zero Trust
1. Verified identity
MFA mandatory for all users without exceptions — accounts with MFA activated are 99.9% harder to compromise. Conditional Access evaluating the context of each request. Least privilege access: each user accesses only what they need. In Microsoft 365, this is implemented with Microsoft Entra ID.
2. Managed and verified devices
Microsoft Intune allows registering and managing all devices from a centralized console, applying security policies (encryption, antivirus, updates), and creating compliance policies that block access from non-secure devices.
3. Protected and classified data
Microsoft Purview allows labeling documents by sensitivity, applying protections that travel with the document, and configuring DLP policies to prevent sensitive information from leaving through unauthorized channels.
The Zero Trust roadmap for SMEs: phase by phase
Phase 1 (weeks 1–4): Activate MFA for all users, configure Entra ID Security Defaults, review and remove former employee accounts. Estimated time: 3–5 days. Additional cost: €0 with M365 Business Standard or higher.
Phase 2 (weeks 4–8): Activate and configure Microsoft Intune, enroll corporate devices, create basic compliance policies. Included in Microsoft 365 Business Premium.
Phase 3 (weeks 8–12): Implement sensitivity labels with Purview, configure basic DLP policies for email and SharePoint, train users.
If you want to understand what security controls you have and what the most critical gaps are, I offer a Microsoft 365 security audit.