What Is Zero Trust Security and Do I Need It?

Quick answer: Zero Trust is a security model where nothing is trusted by default—not users, not devices, not networks. Every access request is verified, regardless of where it comes from. It's not a product you buy; it's an approach you implement across identity, devices, network, applications, and data.

The Core Principle

Old model: Trust but verify. Inside the network = trusted. Outside = untrusted.

Zero Trust: Never trust, always verify. Every access request is authenticated and authorised, every time, regardless of location.

Why the shift:

• Perimeters don't exist anymore (cloud, remote work, mobile)
• Attackers inside the network can move freely
• VPNs give too much access once connected
• Credentials get stolen; implicit trust is exploited

Zero Trust Principles

1. Verify explicitly

Authenticate and authorise based on all available data points:

• User identity
• Device health
• Location
• Resource sensitivity
• Anomaly detection

Don't just check username and password. Check everything.

2. Use least privilege access

• Minimum permissions necessary
• Just-in-time access (grant when needed, revoke when done)
• Just-enough access (only what's required for the task)

If someone's account is compromised, limit the damage.

3. Assume breach

• Design as if attackers are already inside
• Segment access to limit lateral movement
• Monitor and log everything
• Detect and respond quickly

Don't assume the perimeter will hold.

Zero Trust in Practice

Identity:

• Strong authentication (MFA everywhere)
• Conditional Access policies
• Privileged access management
• Identity threat detection

Devices:

• Device health verification
• Endpoint compliance requirements
• Certificate-based trust
• Managed device requirements for sensitive access

Network:

• Micro-segmentation
• No implicit trust for internal traffic
• Encrypted communications
• Software-defined perimeter

Applications:

• Application-level authentication
• API security
• Integration verification
• Activity monitoring

Data:

• Classification and labelling
• Encryption at rest and in transit
• Data Loss Prevention
• Access logging

Microsoft's Zero Trust Stack

For Microsoft 365 environments, Zero Trust implementation includes:

Entra ID (Azure AD):

• Conditional Access policies
• Identity Protection
• Privileged Identity Management

Intune:

• Device compliance policies
• App protection policies
• Conditional Access based on device health

Defender:

• Threat protection across endpoints, email, identity
• Integrated security signals

Purview:

• Data classification
• DLP policies
• Information protection

These tools enable Zero Trust—but they need proper configuration.

Do You Need Zero Trust?

Yes if:

• You have remote/hybrid workers
• You use cloud services
• You have sensitive data
• You've outgrown VPN-based access
• Compliance frameworks reference it (they all do now)
• You want meaningful security improvement

The reality: You probably need Zero Trust principles even if you don't use the buzzword. The question is how far to go.

Starting Your Journey

Phase 1: Identity foundation

• MFA everywhere
• Conditional Access policies
• Review admin accounts
• Implement privileged access management

Phase 2: Device trust

• Endpoint compliance policies
• Require managed devices for sensitive access
• Device health attestation

Phase 3: Network segmentation

• Reduce flat network reliance
• Segment sensitive resources
• Consider SASE/SSE for network security

Phase 4: Application and data

• Application-level controls
• Data classification
• DLP implementation

What We Implement

Zero Trust isn't a product purchase—it's a transformation. We help clients:

• Assess current state against Zero Trust principles
• Design architecture appropriate for their environment
• Implement controls (identity, device, network, data)
• Manage ongoing (Conditional Access, compliance, monitoring)

Microsoft 365 provides excellent Zero Trust building blocks. Most organisations have them—they just haven't configured them.

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