Cybersecurity researchers have identified a critical design flaw in the delegated Managed Service Accounts (dMSAs) in Windows Server 2025. This vulnerability could enable high-impact attacks that allow adversaries to move laterally across domains and maintain persistent access to managed service accounts within Active Directory.
According to a report by Semperis, the flaw allows attackers to circumvent authentication safeguards and generate passwords for all dMSAs and group Managed Service Accounts (gMSAs). The technique, dubbed Golden dMSA, is considered low in complexity because it facilitates easy brute-force password generation.
To exploit this vulnerability, attackers need access to a Key Distribution Service (KDS) root key, which is usually restricted to privileged accounts like Domain Admins. This root key acts as a master key, enabling the attacker to derive passwords for any dMSA or gMSA throughout the network without directly interacting with the domain controller.
The vulnerability arises from predictable time-based components within the password-generation mechanism, limiting possible combinations to just 1,024, making it vulnerable to brute-force attacks. Once an attacker gains elevated privileges, they can exploit this flaw by following a series of steps, which include extracting KDS root key material, enumerating dMSA accounts, identifying password hashes, and generating valid Kerberos tickets for compromised accounts.
Malyanker, a security researcher, highlighted that this attack method poses a critical risk as it allows unauthorized access to all dMSAs across the entire forest of Active Directory by compromising a single KDS root key.
Additionally, this technique effectively transforms a breach into a forest-wide persistent backdoor, providing attackers with extensive control, including cross-domain account compromise and credential harvesting.
Despite the automation of password rotations intended to protect dMSAs, privileged accounts can bypass these safeguards, making the Golden dMSA a particularly dangerous exploit. Microsoft has indicated that the existing features do not protect against compromises of a domain controller, underscoring the vulnerability’s severity.
For more details, refer to the original reports and discussions regarding this vulnerability and recommended protective measures.
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