Recovering Active ADFS Signing Keys via Machine DPAPI
Written by: Shebin Mathew
Introduction
The "Golden SAML" technique, first described by CyberArk researchers in 2017, and further detailed by Mandiant researchers in 2021, remains one of the most effective methods for threat actors to forge identity assertions in the Microsoft ecosystem. By obtaining the private key of an ADFS token-signing certificate, an attacker can authenticate as any user to any SAML-federated application, bypassing multifactor authentication (MFA), conditional access, and all identity-based controls.
However, during a recent red team engagement, Mandiant discovered that when ADFS certificates are manually rotated, configuration drift can silently leave active signing keys exposed in Machine DPAPI. Specifically, Mandiant discovered that in environments where AutoCertificateRollover is disabled and certificates are manually rotated, the database often becomes a 'ghost'—a record that still exists, still decrypts successfully, but references a certificate no longer used for token signing by the ADFS service. This attack vector warrants attention because...
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