How do you implement A.8.3 in Microsoft 365?

A.8.3 Information Access Restriction can be implemented in Microsoft 365 using Microsoft Entra admin center (entra.microsoft.com) > Protection > Conditional Access. Contact Global Micro Solutions for a detailed implementation guide.

What does an auditor check for A.8.3?

Auditors verify that A.8.3 Information Access Restriction is properly implemented by reviewing evidence from your M365 tenant, checking configuration against ISO 27001 requirements, and validating compliance documentation.

ISO 27001 A.8.3: Information Access Restriction — M365 Implementation Guide | Global Micro Solutions

What is this control?

ISO 27001 control A.8.3 Information Access Restriction implements layered Zero Trust-based access restrictions across Microsoft 365 and Azure to enforce deny-by-default access controls. Layer 1 enforces strong authentication and device compliance via Conditional Access. Layer 2 implements least privilege through RBAC for Azure and Microsoft 365 Groups for SharePoint and Teams.

Layer 3 applies Sensitivity Labels with persistent encryption. Layer 4 conducts periodic access reviews. Customer Lockbox requires explicit approval before Microsoft engineers access organisational content.

How to implement in Microsoft 365

Implement A.8.3 by deploying Conditional Access Policies requiring MFA, device compliance, and low user risk for access. Configure Device Compliance via Intune requiring encryption, password policy, and AV signature currency. Implement RBAC for Azure using Azure Role-Based Access Control to assign permissions to security groups rather than individuals.

Configure Microsoft 365 Groups to manage access to SharePoint, Teams, and OneDrive. Disable Anyone sharing links tenant-wide and enforce Specific people sharing. Deploy Sensitivity Labels with encryption for Confidential and Sensitive labels.

Enable Customer Lockbox in Microsoft 365 admin centre.

What an auditor looks for

Auditors will verify active Conditional Access policies enforcing MFA with at least one policy required. They will check device compliance requirements are enforced via CA. Auditors will review Identity Protection configuration blocking high-risk users.

They will verify access reviews are configured and recently completed for privileged groups. Auditors will check Sensitivity Label configuration with encryption enabled for Confidential and Sensitive labels. They will verify external sharing policies are set to Specific people only and Customer Lockbox is enabled.