Microsoft 365 and Entra ID Penetration Testing

Why the Tenant Is the New Perimeter

When an organization moves email, files, and sign-ins to Microsoft 365, the Entra ID tenant becomes the thing that decides who gets in and what they can reach. An attacker no longer has to breach a firewall; they have to defeat a login page and the conditional access rules behind it. That is why testing the tenant directly, rather than only the on-prem network, has become essential for cloud-first and hybrid organizations.

What the Test Covers

A Microsoft 365 and Entra ID penetration test combines a configuration review with authorized attack simulation. The review examines multi-factor and conditional access coverage, privileged role assignments, legacy authentication, app registrations and OAuth consent, and guest and external sharing. The attack phase, run with permission and coordinated with your team, validates which of those weaknesses an outsider could actually use.

• Multi-factor enrollment gaps and conditional access exclusions
• Legacy authentication paths that bypass modern controls
• Global Administrator sprawl and standing privileged access
• Over-permissive app registrations and risky OAuth consent settings
• Guest accounts and sharing links that expose data externally

Common Findings

Across tenant engagements the same issues recur: a handful of accounts enrolled in no second factor, conditional access policies with a trusted-location exclusion that effectively disables them, service accounts holding Global Administrator, and third-party applications granted broad, standing access to mail and files. None of these require a software exploit, which is why a configuration-aware test finds them where a scanner would not. Our guide to Microsoft 365 security hardening covers how to close them.

How It Relates to Internal Network Testing

If you still run on-prem Active Directory, a tenant test and an internal network penetration test cover different ground and are best run together, because hybrid identity means a compromise on one side often reaches the other. If you are fully cloud with no on-prem servers, the tenant test is the one that matters most.

Frequently Asked Questions

What is Microsoft 365 penetration testing?

Microsoft 365 penetration testing is an authorized assessment of your Microsoft 365 and Entra ID tenant. It combines a configuration review of controls such as multi-factor authentication, conditional access, privileged roles, and OAuth consent with permitted simulation of the techniques attackers use against cloud tenants, to prove what a given weakness would actually allow.

Do I need Microsoft's permission to test my tenant?

You do not need to notify Microsoft in advance to test your own tenant, but testing must follow Microsoft's published rules of engagement, and it requires written authorization from your organization. Grid32 confirms authorization and agrees the boundaries in the Statement of Work before any testing begins.

What access does Grid32 need to test Microsoft 365 or Entra ID?

The configuration review runs from read-only roles such as Global Reader and Security Reader. The attack-simulation phase uses an authorized user list and one or two low-privilege test accounts that you create. No write access to your tenant is required. We agree the exact access before the engagement starts.

Does this cover Google Workspace too?

Yes. The same assessment applies to Google Workspace, reviewed against the equivalent identity, access, and sharing controls, with read-only admin visibility for the review and authorized test accounts for the access-dependent checks.