Well-Known Security Identifiers

A security identifier (SID) is a unique value of variable length that is used to identify a security principal or security group in Microsoft® Windows® 2000 and Microsoft® Windows NT®. Well-known SIDs are a group of SIDs that identify generic users or generic groups. Their values remain constant. Table E.1 is a list of all SIDs in this category.

For information about how SIDs are assigned and used, see "Access Control" in this book.

Table E.1 Well-Known Security Identifiers

SID	Name	Description
S-1-0	Null Authority	An identifier authority.
S-1-0-0	Nobody	No security principal.
S-1-1	World Authority	An identifier authority.
S-1-1-0	Everyone	A group that includes all users, even anonymous users and guests. Membership is controlled by the operating system.
S-1-2	Local Authority	An identifier authority.
S-1-3	Creator Authority	An identifier authority.
S-1-3-0	Creator Owner	A placeholder in an inheritable access control entry (ACE). When the ACE is inherited, the system replaces this SID with the SID for the object's current owner.
S-1-3-1	Creator Group	A placeholder in an inheritable ACE. When the ACE is inherited, the system replaces this SID with the SID for the primary group of the object's current owner. The primary group is used only by the POSIX subsystem.
S-1-3-2	Creator Owner Server	[SID not used in Windows 2000.]
S-1-3-3	Creator Group Server	[SID not used in Windows 2000.]
S-1-4	Nonunique Authority	An identifier authority.
S-1-5	NT Authority	An identifier authority.
S-1-5-1	Dialup	A group that implicitly includes all users who are logged on to the system through a dial-up connection. Membership is controlled by the operating system.
S-1-5-2	Network	A group that implicitly includes all users who are logged on through a network connection. Membership is controlled by the operating system.
S-1-5-3	Batch	A group that implicitly includes all users who have logged on through a batch queue facility such as task scheduler jobs. Membership is controlled by the operating system.
S-1-5-4	Interactive	A group that includes all users who have logged on interactively. Membership is controlled by the operating system.
S-1-5-5-X-Y	Logon Session	A logon session. The X and Y values for these SIDs uniquely identify a particular logon session.
S-1-5-6	Service	A group that includes all security principals that have logged on as a service. Membership is controlled by the operating system.
S-1-5-7	Anonymous	A user who has logged on anonymously.
S-1-5-8	Proxy	[SID not used in Windows 2000.]
S-1-5-9	Enterprise Controllers	A group that includes all domain controllers an Active Directory^™ directory service forest of domains. Membership is controlled by the operating system.
S-1-5-10	Principal Self (or Self)	A placeholder in an ACE on a user, group, or computer object in Active Directory. When you grant permissions to Principal Self, you grant them to the security principal represented by the object. During an access check, the operating system replaces the SID for Principal Self with the SID for the security principal represented by the object.
S-1-5-11	Authenticated Users	A group that includes all users whose identities were authenticated when they logged on. Membership is controlled by the operating system.
S-1-5-12	Restricted Code	[SID reserved for future use.]
S-1-5-13	Terminal Server Users	A group that includes all users who have logged on to a Terminal Services server. Membership is controlled by the operating system.
S-1-5-18	Local System	A service account that is used by the operating system.
S-1-5-<domain>-500	Administrator	A user account for the system administrator. This account is the first account created during operating system installation. The account cannot be deleted or locked out. It is a member of the Administrators group and cannot be removed from that group.
S-1-5-<domain>-501	Guest	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.
S-1-5-<domain>-502	KRBTGT	A service account that is used by the Key Distribution Center (KDC) service.
S-1-5-<domain>-512	Domain Admins	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 in the domain's Active Directory by any member of the group. If members of the group create other objects, such as files, the default owner is the Administrators group.
S-1-5-<domain>-513	Domain Users	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 automatically.
S-1-5-<domain>-514	Domain Guests	A global group that, by default, has only one member, the domain's built-in Guest account.
S-1-5-<domain>-515	Domain Computers	A global group that includes all computers that have joined the domain, excluding domain controllers.
S-1-5-<domain>-516	Domain Controllers	A global group that includes all domain controllers in the domain. New domain controllers are added to this group automatically.
S-1-5-<domain>-517	Cert Publishers	A global group that includes all computers that are running an enterprise certificate authority. Cert Publishers are authorized to publish certificates for User objects in Active Directory.
S-1-5-<root domain>-518	Schema Admins	A group that exists only in the root domain of an Active Directory forest of domains. It is a universal group if the domain is in native mode, a global group if the domain is in mixed mode. 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.
S-1-5-<root domain>-519	Enterprise Admins	A group that exists only in the root domain of an Active Directory forest of domains. It is a universal group if the domain is in native mode, a global group if the domain is in mixed mode. 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.
S-1-5-<domain>-520	Group Policy Creators Owners	A global group that is authorized to create new Group Policy objects in Active Directory. By default, the only member of the group is Administrator. The default owner of a new Group Policy object is usually the user who created it. If the user is a member of Administrators or Domain Admins, all objects that are created by the user are owned by the group. Owners have full control of the objects they own.
S-1-5-<domain>-553	RAS and IAS Servers	A domain local group. By default, this group has no members. Computers that are running the Routing and Remote Access service are added to the group automatically. Members of this group have access to certain properties of User objects, such as Read Account Restrictions, Read Logon Information, and Read Remote Access Information.
S-1-5-32-544	Administrators	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. The Administrators group has built-in capabilties that give its members full control over the system. The group is the default owner of any object that is created by a member of the group.
S-1-5-32-545	Users	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. Users can perform tasks such as running applications, using local and network printers, shutting down the computer, and locking the computer. Users can install applications that only they are allowed to use if the installation program of the application supports per-user installation.
S-1-5-32-546	Guests	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.
S-1-5-32-547	Power Users	A built-in group. By default, the group has no members. This group does not exist on domain controllers. Power Users can create local users and groups; modify and delete accounts that they have created; and remove users from the Power Users, Users, and Guests groups. Power Users also can install most applications; create, manage, and delete local printers; and create and delete file shares.
S-1-5-32-548	Account Operators	A built-in group that exists only on domain controllers. By default, the group has no members. By default, Account Operators have permission to create, modify, and delete accounts for users, groups, and computers in all containers and organizational units (OUs) of Active Directory except the Builtin container and the Domain Controllers OU. Account Operators do not have permission to modify the Administrators and Domain Admins groups, nor do they have permission to modify the accounts for members of those groups.
S-1-5-32-549	Server Operators	A built-in group that exists only on domain controllers. By default, the group has no members. Server Operators can log on to a server interactively; create and delete network shares; start and stop services; back up and restore files; format the hard disk of the computer; and shut down the computer.
S-1-5-32-550	Print Operators	A built-in group that exists only on domain controllers. By default, the only member is the Domain Users group. Print Operators can manage printers and document queues.
S-1-5-32-551	Backup Operators	A built-in group. By default, the group has no members. Backup Operators can back up and restore all files on a computer, regardless of the permissions that protect those files. Backup Operators also can log on to the computer and shut it down.
S-1-5-32-552	Replicators	Not used in Windows 2000. In Windows NT domains, it is a built-in group used by the File Replication service on domain controllers.