Well-Known Security Identifiers (SIDs)

Similar to TCP ports, have you ever wondered what all the different Windows SIDs are reserved for? Down below is a quick list of common Well-Known SIDs, and at the bottom of this post you'll find a link to the MKB article with an almost complete list.

First off, here's how a SID breaks down:

Example: S-1-5-21-1674060341-653213906-1520766640-1984

The first character is always an S. It identifies it as a SID

The first number is the SID revision level.

The second number identifies the authority (5 is NT authority)

The third of set of numbers is the domain or local computer identifier
(in this case: 21-1674060341-653213906-1520766640)

The final number (after the last hyphen) is the RID (Registered ID). Any RID that is 1000 or higher is part of a SID generated by the domain's RID Master. RIDs less than 1000 are built-in or created by default and reserved (for example, 500 on the end is reserved for the Administrator account). In the above example, 1984 refers to a created user object's SID.

		SID: S-1-5-domain-501 Name: Guest Description: A user account for people who do not have individual accounts. This user account does not require a password. By default, the Guest account is disabled.
		SID: S-1-5-domain-512 Name: Domain Admins Description: A global group whose members are authorized to administer the domain. By default, the Domain Admins group is a member of the Administrators group on all computers that have joined a domain, including the domain controllers. Domain Admins is the default owner of any object that is created by any member of the group.
		SID: S-1-5-domain-513 Name: Domain Users Description: A global group that, by default, includes all user accounts in a domain. When you create a user account in a domain, it is added to this group by default.
		SID: S-1-5-domain-514 Name: Domain Guests Description: A global group that, by default, has only one member, the domain's built-in Guest account.
		SID: S-1-5-domain-515 Name: Domain Computers Description: A global group that includes all clients and servers that have joined the domain.
		SID: S-1-5-domain-516 Name: Domain Controllers Description: A global group that includes all domain controllers in the domain. New domain controllers are added to this group by default.
		SID: S-1-5-root domain-518 Name: Schema Admins Description: A universal group in a native-mode domain; a global group in a mixed-mode domain. The group is authorized to make schema changes in Active Directory. By default, the only member of the group is the Administrator account for the forest root domain.
		SID: S-1-5-root domain-519 Name: Enterprise Admins Description: A universal group in a native-mode domain; a global group in a mixed-mode domain. The group is authorized to make forest-wide changes in Active Directory, such as adding child domains. By default, the only member of the group is the Administrator account for the forest root domain.
		SID: S-1-5-32-544 Name: Administrators Description: A built-in group. After the initial installation of the operating system, the only member of the group is the Administrator account. When a computer joins a domain, the Domain Admins group is added to the Administrators group. When a server becomes a domain controller, the Enterprise Admins group also is added to the Administrators group.
		SID: S-1-5-32-545 Name: Users Description: A built-in group. After the initial installation of the operating system, the only member is the Authenticated Users group. When a computer joins a domain, the Domain Users group is added to the Users group on the computer.
		SID: S-1-5-32-546 Name: Guests Description: A built-in group. By default, the only member is the Guest account. The Guests group allows occasional or one-time users to log on with limited privileges to a computer's built-in Guest account.

Well-known security identifiers in Windows operating systems