How do you configure TLS inspection in Microsoft Global Secure Access?

What TLS inspection changes in Microsoft Global Secure Access

TLS inspection changes the service from a simple encrypted-traffic relay into an inspection point for selected HTTPS sessions. That means you are not just turning on visibility, you are deciding which traffic should be decrypted, where trust anchors must exist, and which users and destinations should remain exempt because inspection would create breakage or unacceptable sensitivity exposure.

For practical deployment, the key design choice is scope. Inspect only the traffic categories that need policy enforcement or threat visibility, then align the client or routing path so the service can see that traffic consistently. If the device does not trust the inspection certificate chain, or if the traffic path bypasses the service, inspection will fail silently or degrade into inconsistent results.

The most important operational consequence is application compatibility. Certificate-pinned, mutual-TLS, or highly sensitive application flows can fail when decrypted, so those workloads need explicit exceptions and validation before rollout. That makes TLS inspection less like a blanket security feature and more like a controlled policy that must be engineered around specific trust assumptions.

How to deploy the inspection path safely

Start with the network and endpoint path, then move to policy scope. Configure the required Global Secure Access client or forwarding/routing components first, because inspection cannot work if eligible traffic never enters the managed path. Next, distribute and trust the inspection certificate on managed devices so the client can validate the decrypted session without user disruption.

Use group-based targeting rather than broad tenant-wide activation. A narrower scope gives you a cleaner test set for validating proxy behaviour, certificate trust, authentication flows, and app compatibility. It also reduces the chance that you will interrupt services that depend on certificate pinning, nonstandard TLS behaviour, or embedded trust stores.

When you define traffic categories, separate what you want to inspect from what you merely can inspect. The useful rule is that inspection should support a concrete security decision, such as malware detection, web policy enforcement, or data-loss review. If a category does not justify decryption, leave it encrypted and document the exemption.

Good rollout practice is to test with a small, representative user group, confirm that decrypted sessions are readable by the service, and verify that the destination applications still behave normally. That validation matters more than the toggle itself, because inspection succeeds technically only when endpoint trust, path steering, and application compatibility all line up.

Where TLS inspection tends to fail in practice

Most failures come from trust, scope, or application design. If the inspection certificate is not trusted on the endpoint, browsers and apps will reject the substituted certificate chain. If routing is inconsistent, some flows will be inspected and others will bypass the service, which creates gaps that are hard to spot during testing.

The other common failure mode is over-inspection. Teams sometimes expand decryption too far because the control is available, then discover that sensitive systems, certificate-pinned apps, or regulated workflows are too brittle to tolerate it. In those cases, the safer answer is a narrowly carved exception list backed by a documented reason rather than forcing inspection everywhere.

Inspection also changes your trust boundary. Once traffic is decrypted in the service, you must treat the inspection point as security-sensitive infrastructure, because it now sees content that was previously protected end to end. That makes certificate protection, access control, and logging around the inspection service part of the control, not an afterthought.

Risk and Threat Considerations

TLS inspection creates both visibility and exposure. It improves detection on encrypted web traffic, but it also concentrates decryption trust in one place, which means a misconfiguration or compromise of the inspection path can expose content, weaken privacy expectations, or break applications that rely on certificate pinning or mutual trust.

Failure mechanism: If the inspection certificate is mishandled, not trusted, or deployed too broadly, the service can either fail open with blind spots or fail closed with application outages. Overbroad decryption can also reveal sensitive payloads to controls that were never meant to see them.

Impact: The result can be loss of confidentiality, user disruption, and inconsistent enforcement, especially when exceptions are not documented or when critical applications depend on nonstandard TLS behaviour.

Practitioner Guidance

What to verify: Confirm that the service certificate is trusted on every managed endpoint in scope, then test a representative mix of browsers, line-of-business apps, and certificate-pinned services before expanding the policy. If any critical app fails during inspection, treat that as a design issue, not just a troubleshooting issue.

Decision rule: If inspection provides no clear policy or threat-detection value for a traffic class, leave it out. If a flow is sensitive, pinned, or operationally fragile, exclude it first and only reintroduce it after a documented compatibility test.

Practitioner takeaway: TLS inspection works best when it is selective, testable, and exception-driven, because the control is only as good as the trust path and the application behaviour it preserves.

Related resources from NHI Mgmt Group

• Guide: TLS Inspection Guide
• How do you discover AI agents in use with Microsoft Global Secure Access?
• How do you secure Model Context Protocol traffic with Microsoft Global Secure Access?
• How do you discover shadow AI usage with Microsoft Entra Global Secure Access?
• How do you secure AI agent identities with Microsoft Entra Conditional Access?