Zero Trust is one of the most talked-about concepts in IT security in recent years. It sounds technical and complex, but the principle is actually very simple: never trust anyone or anything by default. Always verify. It is a fundamentally different approach than the traditional way of thinking about network security.

The old paradigm: castle and moat

The classic security model works like a medieval castle. Outside the walls is dangerous, inside the walls is safe. Once you have passed through the gate (the firewall), the system trusts you. You are "in," and then you are free to move about.

The problem with that model is that it breaks down in modern reality:

  • Employees work from home: they are never "in" the office
  • Data lives in the cloud, not behind the firewall
  • Vendors and consultants have access, and are not your own people
  • Compromised user accounts can move freely once they are "inside the walls"

Attackers know this. Once they have gained access to one account, they move laterally, from system to system, and escalate privileges until they have access to what they want. A Zero Trust approach significantly limits this.

Zero Trust in practice: four concrete elements

1. Verify identity, always

MFA (multifactor authentication) on all systems is the foundation. A user logging in must prove their identity with more than just a password. This applies regardless of whether they are at the office, at home, or abroad.

2. Least possible privileges

The principle of least privilege means that a user only has access to exactly what they need to do their job. An employee in accounting does not need access to the HR system. A salesperson does not need access to the production database. The fewer the privileges, the less damage a compromised account can do.

3. Device health status

Zero Trust checks who you are and also what device you use. Is the computer updated? Is antivirus active? Is it encrypted? An unknown or unhealthy device is rejected or restricted, even if the user is verified.

4. Network segmentation

Divide your network so that a compromised device or user does not automatically have access to all systems. Guest Wi-Fi, IoT devices, and production systems should exist on separate network segments.

You do not need to start from scratch. Many Zero Trust elements are already available in Microsoft 365 and Entra ID. Conditional Access, MFA, and device management are Zero Trust in practice, even if they are not always marketed under that name.

Is Zero Trust relevant for an SMB?

Yes, but adapted to your size. You do not need a dedicated Zero Trust architect. Three measures give you most of the benefit:

  1. MFA everywhere: email, Microsoft 365, VPN, all critical systems
  2. Review of access rights: who has access to what? Delete unnecessary privileges
  3. Separate network: guests and IoT devices on their own Wi-Fi segment

It is not rocket science. It is good, systematic IT hygiene, and that is the core of Zero Trust.