Synthèse
Analysts followed the standard DKM extraction path, retrieving the encrypted blob from the WID database and decrypting it using the DKM material stored in Active Directory. The extraction succeeded, but the recovered certificate was no longer valid for token signing, and Entra ID rejected the resulting tokens with AADSTS500172 due to invalid signing material. Although structurally correct, the artifact is not usable for authentication, as the active signing key resides in the system’s machine-sc
Analysts followed the standard DKM extraction path, retrieving the encrypted blob from the WID database and decrypting it using the DKM material stored in Active Directory. The extraction succeeded, but the recovered certificate was no longer valid for token signing, and Entra ID rejected the resulting tokens with AADSTS500172 due to invalid signing material. Although structurally correct, the artifact is not usable for authentication, as the active signing key resides in the system’s machine-scoped cryptographic store, protected by Windows Machine DPAPI and managed through the operating system’s cryptographic subsystem. Successfully obtaining this active key allows an attacker to forge valid SAML assertions for any user, bypassing the need for user credentials and multi-factor authentication, and granting unauthorized access to any SAML-federated application including Microsoft 365 and Entra ID within the organization's environment. Analysis revealed that AutoCertificateRollover had been disabled and a manual rotation had been performed.
Confirmation was obtained directly via Get-AdfsProperties, which returned AutoCertificateRollover: False, indicating that certificate lifecycle management had been delegated to manual administrative processes. While the ADFS service used a new valid key for signing, the WID configuration database was never updated to reflect the new certificate—leaving an expired "ghost" entry as the only record. This drift condition surfaces via Microsoft Event ID 385, which indicates certificate validity warnings in the ADFS service. Notably, this event self-resolves when AutoCertificateRollover is re-enabled and a subsequent certificate rollover is performed; in environments where it is disabled and manual rotation is performed without a corresponding database update, it is the observable symptom of this drift condition.