Microsoft’s Credential Guard considerations and known-issues guidance documents compatibility implications and scenarios that require planning. Credential Guard uses virtualization-based security, and enabling or disabling it can interact with operating-system defaults, policy, firmware, virtual machines, and deployment method.
\nMicrosoft’s technical overview explains that isolated LSA stores selected Kerberos, NTLM, and Credential Manager secrets outside the ordinary operating-system process using VBS. It also states protection limits. Credential Guard does not protect credentials managed outside Windows protections, keyloggers, physical attacks, the Active Directory database on a domain controller, or every credential supplied to legacy authentication.
\nThe documentation describes protocol effects: certain uses of NTLMv1, MS-CHAPv2, Digest, CredSSP, unconstrained delegation, and DES can no longer use signed-in credentials as before. Exact defaults, hardware requirements, support, and behavior vary by Windows edition, version, device role, virtualization platform, and policy. Review current Microsoft and product-vendor documentation for the target fleet.
\n\nDo not begin by forcing the policy across the fleet. Build a readiness inventory that connects devices to business workflows and authentication dependencies. Include privileged workstations, standard laptops, shared workstations, kiosks, jump hosts, servers used interactively, virtual desktops, VPN, Wi-Fi, RDP, file and print, line-of-business applications, smart cards, third-party credential providers, endpoint security, and backup or recovery tools.
\nSeparate Credential Guard from Remote Credential Guard, LSA protection, Windows Hello, and other related features in design and test records; they have different requirements and boundaries. Protect the hypervisor and host of virtual machines, because in-guest isolation does not defend against a privileged host attack.
\nRetest after major Windows, firmware, hypervisor, VPN, security-agent, or application changes. The completion record should list supported devices, workflows exercised, remaining legacy dependencies, exceptions, and recovery results. Credential Guard reduces specific credential-theft paths; it is not a substitute for privileged-access separation, patching, phishing resistance, endpoint protection, or least privilege.
\nUse an exit gate for every deployment ring: all required workflows pass, recovery was demonstrated, state reporting is reliable, support can recognize known errors, and every exception has an owner and end condition. Stop on widespread fallback prompts, lost remote administration, incompatible security software, or inability to boot and recover. Preserve diagnostic evidence, restore the approved configuration, remediate the dependency, and rerun the full ring.
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