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AD Rights Management Service (Part 2): Extraction, Offline Decryption, and the Unrotatable Key

Huntress research shows AD RMS SLC root key is unrotatable and never expires, so its compromise permanently exposes all RMS-protected documents.

Part 2 of Huntress's AD RMS series details server-side attacks: extracting the Server Licensor Certificate (SLC) private key and performing offline decryption of protected documents. The SLC key has no expiry or rotation mechanism, with a 255-year certificate validity (2002–2258), so whoever recovers it can decrypt every document the deployment ever protected, indefinitely. The author released SharpRMS, a unified tool combining the 2016 DisARMS client-side attacks with new server-side key extraction and decryption capabilities. The research frames the SLC as comparable to KRBTGT and the DPAPI domain backup key, though not equivalent to domain compromise.

Huntress · 5d agoResearch

AD Rights Management Service (Part 1): Architecture, Deprecation, and Reconnaissance

Huntress maps AD RMS architecture and recon paths, setting up an offline key-extraction attack against its unrotatable 255-year root key.

Huntress's multi-part research examines Active Directory Rights Management Services, Microsoft's enterprise DRM role that still ships in Windows Server 2025 despite migration guidance favoring Azure Information Protection. Part 1 covers the trust model and how an ordinary domain account can locate RMS clusters and read rights-policy templates. Part 2 will detail four independent paths for extracting the Server Licensor Certificate (SLC) private key via service-group membership and the configuration database, enabling fully offline decryption of protected documents. The SLC certificate is valid from 2002 to 2258 and has no key-rotation mechanism, so a stolen key decrypts protected content indefinitely.

Huntress · 7d agoResearch1