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How to configure Domain for windows servers.

    Default Access Control Settings in Windows 2000 This white paper describes the default security settings for components of the Microsoft? Windows? 2000 operating system, including the registry and file system, as well as user rights and group membership. Implications for developers and system administrators are discussed, and answers to frequently asked questions are provided.

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    Default Access Control Settings for Windows 2000

    Summary

    Frequently Asked Questions

    Appendix A: Default File System ACLs for Power Users and Users

    Appendix B: Default Registry ACLs for Power Users and Users

    Default Access Control Settings for Windows 2000

    Overview

    A significant portion of the Windows 2000 operating system security is defined by the default access permissions granted to three groups: Administrators, Power Users, and Users. At a very high level, these groups may be described as follows:

    Administrators are all-powerful. The default Windows 2000 security settings do not restrict administrative access to any registry or file system object. Administrators can perform any and all functions supported by the operating system. Any right that the administrator does not have by default, they can grant to themselves.

    Ideally, administrative access to the system should only be needed to:

    Install the operating system and components (including drivers for hardware, system services, and so forth).

    Install Service Packs and hotfixes.

    Install Windows updates.

    Upgrade the operating system

    Repair the operating system.

    Configure critical machine-wide operating system parameters, for example, kernel mode driver configuration, password policy, access control, and audit functions.

    In practice, administrative accounts must often be used to install and run legacy Windows-based applications.

    Users are the opposite of administrators. Provided that the Windows 2000 operating system is clean-installed onto an NTFS partition, the default security settings are designed to prohibit Users from compromising the integrity of the operating system and installed applications. Users cannot modify computer-wide registry settings, operating system files, or program files. Users cannot install applications that can be run by other members of the Users group (preventing Trojan horses).

    Users cannot access other users' private data. Thus, two significant aspects of securing a Windows 2000-based system are as follows:

    1. Make sure that end-users are members of the Users group only.

    2. Deploy applications that members of the Users group can successfully run.

    Ideally, Users should be able to run any application that has been previously installed by an Administrator, Power User, or themselves. Users should not be able to run applications that are installed by other Users.

    In practice, members of the Users group will not be able to run most legacy applications because most legacy applications were not designed with operating system security in mind. Members of the Power Users group should be able to run such applications.

    Applications that comply with the Windows 2000 Application Specification

    (http://msdn.microsoft.com/certification/default.asp) can successfully run in a normal Users context.

    Power Users are ranked between Administrators and Users in terms of system access. The default Windows 2000 security settings for Power Users are backward-compatible with the default security settings for Users in the Windows NT? 4.0 operating system. In short, Power Users are indeed powerful.

    Ideally, Power Users should be able to perform any task except for the administrative tasks described above. Thus, Power Users should be able to:

    Install and remove applications per computer that do not install system services.

    Customize system-wide resources (for example, System Time, Display Settings, Shares, Power Configuration, Printers, and so forth).

    Power Users are not allowed to access other users' data stored on an NTFS partition. In practice, Power Users cannot install many legacy applications, because these applications attempt to replace operating system files during the setup process.

    Configuring Security During Setup

    Default security settings are applied at the beginning of GUI-mode setup during a clean install of Windows 2000 or an upgrade from Windows NT/9x.

    Note: File system security settings can only be applied when the Windows 2000 operating system is installed onto an NTFS partition.

    The default security settings for workstations, servers, and domain controllers can be found in the following files respectively:

    %windir%\inf\defltwk.inf

    %windir%\inf\defltsv.inf

    %windir%\inf\defltdc.inf (Note that default domain controller security settings are applied during DCPromo.)

    Since security is applied at the beginning of GUI-mode setup, no explicit security settings are defined for optional components; for example, Internet Information Services (IIS) or Terminal Services that may be chosen during the GUI-mode phase of setup. This allows optional components to specify their own security if it should be different than what is inherited by default. Default File System and Registry Permissions

    The backward compatible permissions (access control) for Windows 2000 Power Users are included in Appendix A for file system objects and Appendix B for registry objects. The backward compatible default permissions for Power Users are liberal enough that most applications should be able to be installed by a Power User. For example, Power Users have Modify access to:

HKEY_LOCAL_MACHINE \Software

    Program Files

    %windir%

    %windir%\system32

    Even though Power Users have Modify access to the %windir% and %windir%\system32

    directories, Power Users have Read access to the files that are installed in these directories during Windows 2000 text-mode setup. This allows legacy applications to write new files into the system directories, but prevents Power Users from modifying the Windows 2000 system files. Additionally, Power Users are not allowed to install Windows 2000 services.

    The default permissions for Administrators and Users are more easily described as follows: Administrators, System, and Creator Owner are given Full Control to all file system and registry

    objects that exist at the beginning of GUI-mode setup.

    Users are explicitly granted Write access to the locations specified in Table 1.

    Table 1 Users Write Access Locations

    Object Permission Comment

    HKEY_Current_User Full Control User's portion of the registry

    %UserProfile% Full Control User's Profile directory

    All Users\Documents Read, Create Shared Documents Location. Allows

    File Users to create files that can

    subsequently be read (but not

    modified) by other Users.

    %Windir%\Temp Synchronize, Per-Machine temp directory. This is a

    Traverse, Add concession made for service-based

    File, Add applications so that Profiles do not

    Subdir need to be loaded in order to get the

    per-User temp directory of an

    impersonated user.

    \ (Root Directory) Not Not configured during setup because

    Configured the Windows 2000 ACL Inheritance

    during setup model would impact all child objects

    including those outside the scope of

    setup.

    By default, Users have Read (or less) access to the rest of the system.

    It is possible for applications that are installed by administrators to create their own subfolders and specify their own permissions on those subfolders. Certified applications that do not want to inherit the default security settings must create such subfolders in All Users\Documents or All Users\Application Data. For example, an application might want to store a centralized clip-art gallery that any User is allowed to modify. Such configurations should be reviewed by system administrators to determine whether the application functionality requiring this configuration is worth the potential security risk posed by the configuration. Isolating such configurations to these

    two locations (for certified applications), promises to make the task of identifying these potential security vulnerabilities easier.

    Also of note is the fact that permissions on the root directory are not defined during setup. Setup does not change the permissions on the root directory because the Windows 2000 ACL Inheritance model would recursively try to configure all subdirectories of the root. This could result in undesired changes for non-Windows 2000-based directories that may exist on the install partition. Since setup does not change permissions on the root directory, the permissions that previously existed on the root directory are maintained. These root permissions are inherited by any new subdirectories created off of the root, and may be inherited by non-Windows 2000-based directories that already exist off of the root. Thus, after a clean-install setup, the root directory and any non-Windows-based subdirectories should be configured according to the security needs of the organization and the requirements of the applications that need to be run.

    Default User Rights

    The default User rights for clean-installed workstation and member servers are defined in the Table 2. They differ only in one respect and that is in the Shutdownthe system right. On servers, Users

    are not granted this right by default.

    Table 2 Default User Rights

    User Right Default Workstation Default Server

    Replace a Process-Level

    Token

    Generate Security Audits

    Logon as a Batch Job

    Backup Files and Directories Administrators, Backup Ops Administrators, Backup Ops

    Bypass Traverse Checking Administrators, Backup Ops, Administrators, Backup Ops,

    Power Users, Users, Power Users, Users,

    Everyone Everyone

    Create a Pagefile Administrators Administrators

    Create Permanent Shared

    Objects

    Create a Token Object

    Debug Programs Administrators Administrators

    Increase Scheduling Priority Administrators Administrators

    Increase Quotas Administrators Administrators

    Logon Interactively Administrators, Backup Ops, Administrators, Backup Ops,

    Power Users, Users, Guest Power Users, Users, Guest

    Load and Unload Device Administrators Administrators

    User Right Default Workstation Default Server Drivers

    Lock Pages in Memory

    Add workstations to the

    domain

    Access this computer from Administrators, Backup Ops, Administrators, Backup Ops,

    the network Power Users, Users, Power Users, Users,

    Everyone Everyone

    Profile a single process Administrators, Power Users Administrators, Power Users Force shutdown from a Administrators Administrators remote system

    Restore files and directories Administrators, Backup Ops Administrators, Backup Ops Manage audit and security Administrators Administrators logs

    Log on as a service

    Shutdown the system Administrators, Backup Administrators, Backup

    Ops, Power Users, Users Ops, Power Users Modify firmware Administrators Administrators environment variables

    Profile system performance Administrators Administrators Change system time Administrators, Power Users Administrators, Power Users Take ownership of files or Administrators Administrators other objects

    Act as part of the OS

    Deny Interactive Logon

    Deny Batch Logon

    Deny Service Logon

    Deny Network Logon

    Remove Computer from a Administrators, Power Administrators, Power Users,

    Docking Station Users, Users Users

    Synchronize Directory

    Service Data

User Right Default Workstation Default Server

    Enable computer and user

    accounts to be trusted for

    delegation

    1 The Guest account must be enabled before it is allowed to log on interactively. Additional Power User Permissions

    In addition to those capabilities permitted by the default ACLs and User rights, Power Users can also: Create local users and groups.

    Modify users and groups that they have created.

    Create and delete non-admin file shares.

    Create, manage, delete and share local printers.

    Administrators can also perform all of these actions. In the case of account management however, Administrators can create, delete or modify any account, while Power Users can only modify or delete accounts that they themselves have created. Users cannot perform any of these additional Power User actions.

    Default Group Membership

    A significant difference between Windows NT 4.0 and Windows 2000 default security settings is the way access control is assigned in each version of the operating system. In computers running Windows NT 4.0, the Everyone group was used as a catchall for file system ACLs, registry ACLs, and User rights. In a sense, the Everyone group is not a traditional group because an Administrator cannot define who should and should not belong to the group. Instead, the Windows NT operating system or domain automatically controls the group membership so that everyone is a member of the Everyone group. If an administrator wanted more granular access control, the default ACLs would have to be modified in order to remove the Everyone group and add the groups which the administrator could control.

    In the Windows 2000 operating system, a different philosophy is used. Groups such as Everyone and Authenticated Users whose membership is automatically configured by the operating system are not used to assign permissions (There are some exceptions. For example, the Everyone group is used to grant read access to some file system and registry objects for backward compatibility with applications requiring anonymous read access. Also, the interactive group is used on Service ACLs where access depends on how you are logged on to the system rather than who you are logged in as). Instead, only those groups whose membership can be controlled by an administrator are used. Primarily, these are the three user groups discussed in this paper: Users, Power Users, and Administrators.

    The following table, Table 3, describes which users constitute the default membership in these groups. When a user is a member of a group, they automatically have the permissions that have been assigned to that group.

    Table 3 Default members of groups

    Local Group Default Workstation Default Server Members

    Members

    Administrators Administrator Administrator

Local Group Default Workstation Default Server Members

    Members

    Power Users

    Users Authenticated Users, Authenticated Users,

    Interactive Users Interactive Users

    By default, on computers with clean installations, the Authenticated Users group and the Interactive group are added to the Users group on Windows 2000 Professional and Windows 2000 Server-based computers. Membership in the Authenticated Users and Interactive groups is automatically controlled by the operating system. Authenticated Users is the same as the Everyone group except it does not contain anonymous users. Interactive includes anyone who is locally logged on to the system rather than connected over the network.

    Since there are no members of the Power Users group by default, non-administrative users that log on to a Windows 2000-based computer that has been clean-installed onto an NTFS partion will automatically be subject to a secure access control policy. Although these users can run any certified Windows 2000-based application (http://msdn.microsoft.com/certification/default.asp), it is

    likely that they will not be able to successfully run non-certified legacy applications. In order to run legacy applications, one of two things must happen:

    The Users must be added to the Power Users group

    The default security granted to Users must be loosened up

    Since Power Users have at least the same access that Windows NT 4.0 Users had, any application that ran as a User on a Windows NT 4.0-based system should run as a Power User on Windows 2000-based system.

    Finally, when a workstation or server joins a domain, the same domain groups that were added to Windows NT 4.0 local groups are added to Windows 2000-based local groups. Specifically, Domain Administrators and Domain Users are added to the local Administrators and local Users groups respectively upon joining the domain.

    Top of page

    Summary

    A significant portion of the Windows 2000 operating system security is defined by the access permissions granted to three groups: Administrators, Power Users, and Users. By default, on clean-installed NTFS systems, Administrators have complete access to critical operating system components while Users have read access (or less). These default access control settings defined for members of the (non-administrative, non-power) Users group provides a standard, secure Windows-based environment that application developers can target and which is easily testable. Applications that satisfy the Windows 2000 Application Specification

    (http://msdn.microsoft.com/certification/default.asp) can run successfully in the normal Users

    context. Non-certified legacy applications are likely to require increased access such as that granted to Power Users in order to run. Thus, the single most important action customers can take to secure their desktops is to deploy certified applications that can run successfully in the Users context. Until such applications are deployed, the Power Users group provides a convenient, but insecure, backward compatibility mechanism for legacy applications that do not run successfully as a Windows 2000-based User.

    Top of page

Frequently Asked Questions

    What do the Windows 2000 default security settings mean for developers, testers, and system administrators?

    If you are a developer, make sure your code meets the Windows 2000 Application Specification, specifically Chapter 4: "Data and Settings Management." Meeting these requirements offers

    customers maximum security without loss of application functionality and can be marketed as such. If you are a tester, make sure the application you are testing meets the Windows 2000 Application Specification requirements, specifically Chapter 4: "Data and Settings Management." Testing the run-time aspects of the application is straightforward:

    1. Perform a clean installation of the Windows 2000 operating system on an NTFS partition (join a

    domain as necessary).

    2. Log on as an Administrator.

    3. Install the application into the Program Files directory.

    4. Create a test user account (non-administrative).

    5. Log on as the test user created in step 4.

    6. Run the application.

    If you are a system administrator, contact the in-house developers or independent software vendors for each of the applications that are supported in your environment. The Windows 2000 operating system defines a standard secure platform that any developer can target and which is easily tested. Applications are required that can run successfully on this platform. As applications that can successfully run as User are deployed, users can be moved from the Power Users group into the Users group, resulting in significant improvements in security, reliability, and management. Applications that meet the Windows 2000 Application Specification requirements, specifically Chapter 4: "Data and Settings Management," will successfully run as User.

    How can I synchronize upgraded computers with Windows 2000 default security settings?

    Since the security on upgraded computers is not modified during Windows 2000 setup, the default security settings must be applied by an administrator after setup has completed: From the %windir%\security\templates directory, the following command can be run on

    workstations:

    Secedit /configure /cfg basicwk.inf /db basicwk.sdb /log basicwk.log

    /verbose

    For servers, the default security settings are defined in basicsv.inf:

    Secedit /configure /cfg basicsv.inf /db basicsv.sdb /log basicsv.log

    /verbose

    The basic configuration files will apply all default security settings except for User Rights and Group Membership.

    The file system that the Windows 2000 operating system is installed on must be NTFS in order to obtain the default file system ACLs.

    Why is the root directory not secure by default?

    Setup does not change the permissions on the root directory because the Windows 2000 ACL Inheritance model would recursively try to configure all subdirectories of the root. This could result in undesired changes for non-Windows 2000-based directories that may exist on the install partition.

    As a result, administrators should configure root directory security according to their own system configurations and application requirements.

    How will Windows 2000 default security settings impact legacy desktop applications?

    Legacy desktop applications that ran under a User context on computers running Windows NT 4.0 will more than likely have to run under a Power User context on a Windows 2000-based system. By default, non-administrative Users that log onto clean-installed Windows 2000 computers are members of the Users group, so an administrator will need to add these users to the less secure Power Users group in order to run non-certified legacy applications. Applications that meet the Windows 2000 application specification do not require Power User capabilities in order to run successfully.

    How will Windows 2000 default security settings impact legacy server-based applications?

    Server based applications that ran under a User context on computers running Windows NT 4.0 will more than likely need to run under a Power User context in a Windows 2000-based system. Thus, the service accounts for such applications should be added to the Power Users group on Windows 2000 Server platforms in order to achieve backward compatibility with the Windows NT 4.0-based environment.

    Service accounts that ran as local system or under an administrative context are not impacted by the default security settings.

    What applications can successfully run as user?

    Any application that meets the Windows 2000 Application Specification, specifically Chapter 4: "Data

    and Settings Management," will successfully run as User. Note that it is possible for an application to successfully run as User, but still not meet all of the other Windows 2000 Application Specification requirements.

    Why define default security settings that few applications can run on?

    The Internet has changed the threat landscape significantly. In response, customers are demanding secure environments in which to operate. Although the Windows NT operating system provides security mechanisms to meet these demands, these features often cannot be turned on because doing so causes problems for applications written on earlier versions of the Windows operating system. Providing a secure access control policy out of the box sets a standard that ISVs can target and that is easily testable. This, in conjunction with customer demand, will drive the development of security conscious applications necessary the security of any operating system environment. In short, for customers that have fully implemented the Windows 2000 operating system, an application that runs out of the box will have a competitive advantage over an application that does not. Furthermore, an application that runs out of the box on Windows 2000-based computers allows customers to easily secure their desktops simply by making sure that end-users are members of the Users group rather than Power Users or Administrators. Until such applications can be deployed, the Power Users group provides a convenient backward compatibility mechanism for running legacy applications.

    What if I don't want end users to be Power Users when running legacy applications?

    Some system administrators may consider the Power Users group too liberal because of the built-in permissions that members of the Power Users group have:

    Create local users and groups.

    Modify users and groups that they have created.

    Create and delete non-admin file shares.

Create, manage, delete and share local printers.

    All other additional rights, such as Change System Time, or Stop and Start non-autostarted services, can be reconfigured for the Power User by modifying the appropriate user rights or configuring the appropriate ACL.

    Since there is no way to disable the built-in permissions allotted to Power Users, administrators who need to support non-certified legacy applications must loosen up the permissions allotted to members of the Users group to the point where their installed base of applications can be successfully run. The Windows 2000 operating system includes a security template for precisely this purpose. The template is named compatws.inf and can be found in

    the %windir%\security\templates directory. The template can be applied to a system using the Security Configuration Toolset. For example, the secedit.exe command line component of the Toolset can apply the template as follows:

    secedit /configure /cfg compatws.inf /db compatws.sdb

    This template loosens up security for Users in a matter consistent with the requirements of most legacy applications.

    What can an Administrator do that a Power User can't?

    By default, an administrator can:

    Install the operating system.

    Install or configure hardware device drivers, although Power Users are allowed to install Print Drivers.

    Install system services.

    Install Service Packs, hotfixes, and Windows Updates.

    Upgrade the operating system.

    Repair the operating system.

    Install applications that modify Windows system files.

    Configure password policy.

    Configure audit policy.

    Manage security logs.

    Create administrative shares.

    Create administrative accounts.

    Modify groups or accounts created by other users.

    Remotely access the registry.

    Stop or start any service.

    Configure services.

    Increase quotas.

    Increase execution priorities

    Remotely shutdown the system.

    Take ownership of arbitrary objects.

    Assign User rights.

    Override a locked computer.

    Format a hard drive.

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