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S-1-5-21-domain-525: Protected Users

SID Decoder and Well-Known SIDs: Decode a Windows SID (S-1-5-32-544, objectSid hex or Base64, Entra ID S-1-12-1) and look up every well-known SID: Administrators, SYSTEM, Domain Admins…

Paste a SID from a permission list, an event log, whoami /all or a registry key (S-1-5-32-544), or an objectSid in hex or Base64 from an LDAP tool, and see what each part means, which well-known account or group it is, and its other forms. Entra ID SIDs (S-1-12-1-…) are turned back into the object ID, and an object ID into its SID. Domain SIDs you paste are decoded on this page and not put in its address. SIDs and names are Microsoft's (Security identifiers); the explanations are ours.

Try: S-1-5-32-544, S-1-5-18, S-1-1-0, S-1-5-11, S-1-5-21-domain-512, S-1-16-12288

Protected Users
Domain account or group

Members get extra protection: no NTLM, no delegation, no cached credentials, no DES or RC4 Kerberos.

Good for administrator accounts; test first, because it blocks those older methods for its members.

In a real SID the word "domain" is the domain's (or, for local accounts, the computer's) identifier: three numbers, as in S-1-5-21-1004336348-1177238915-682003330-525. Every domain has its own.

Find it in your domain Get-ADObject -Filter "objectSid -eq '$((Get-ADDomain).DomainSID)-525'"