User Account Control (UAC) is a new security component in Windows Vista. UAC enables users to perform common tasks as non-administrators, called standard users in Windows Vista, and as administrators without having to switch users, log off, or use Run As. A standard user account is synonymous with a user account in Windows XP. User accounts that are members of the local Administrators group will run most applications as a standard user. By separating user and administrator functions while enabling productivity, UAC is an important enhancement for Windows Vista.

Note
UAC is also a component of Windows Server 2008.

When an administrator logs on to a computer running Windows Vista, the user is assigned two separate access tokens. Access tokens, which contain a user's group membership and authorization and access control data, are used by Windows® to control what resources and tasks the user can access. Before Windows Vista, an administrator account received only one access token, which included data to grant the user access to all Windows resources. This access control model did not include any failsafe checks to ensure that users truly wanted to perform a task that required their administrative access token. As a result, malicious software could install on users' computers without notifying the users. (This is sometimes referred to as "silent" installation.)

Even more damaging, because the user is an administrator, the malicious software could use the administrator's access control data to infect core operating system files and, in some instances, to become nearly impossible to remove.

The primary difference between a standard user and an administrator in Windows Vista is the level of access the user has over core, protected areas of the computer. Administrators can change system state, turn off the firewall, configure security policy, install a service or a driver that affects every user on the computer, and install software for the entire computer. Standard users cannot perform these tasks and can only install per-user software.

To help prevent malicious software from silently installing and causing computer-wide infection, Microsoft developed the UAC feature. Unlike previous versions of Windows, when an administrator logs on to a computer running Windows Vista, the user’s full administrator access token is split into two access tokens: a full administrator access token and a standard user access token. During the logon process, authorization and access control components that identify an administrator are removed, resulting in a standard user access token. The standard user access token is then used to start the desktop, the Explorer.exe process. Because all applications inherit their access control data from the initial launch of the desktop, they all run as a standard user as well.

After an administrator logs on, the full administrator access token is not invoked until the user attempts to perform an administrative task.

Contrasting with this process, when a standard user logs on, only a standard user access token is created. This standard user access token is then used to start the desktop.

Important
Because the user experience can be configured with Group Policy, there can be different user experiences, depending on policy settings. The configuration choices made in your environment will affect the prompts and dialog boxes seen by standard users, administrators, or both.

This guide is intended for the following audiences:

• IT planners and analysts who are evaluating the product
  
  
• Security architects who are responsible for implementing trustworthy computing
  
  
• Administrators who need to control the behavior of UAC
  
  

• Requirements for User Account Control
  
  
• Key scenarios for User Account Control
  
  
• Scenario 1: Requesting an application to run elevated one time
  
  
• Scenario 2: Marking an application to always run elevated
  
  
• Scenario 3: Configure User Account Control
  
  
• Logging bugs and feedback
  
  
• Additional Resources
  
  

We recommend that you first use the steps provided in this guide in a test environment. Step-by-step guides are not necessarily meant to be used to deploy Windows Vista features without accompanying documentation (as listed in the Additional resources section), and should be used with discretion as a stand-alone document.

Setting up the test lab

This guide covers the following scenarios for UAC:

• Scenario 1: Request an application to run elevated one time
  
  
• Scenario 2: Mark an application to always run elevated
  
  
• Scenario 3: Configure User Account Control
  
  

Note
The three scenarios included in this guide are intended to help administrators become familiar with the UAC feature of Windows Vista. They include the basic information and procedures administrators need to start using UAC. Information and procedures for advanced or customized UAC configurations are not included in this guide.

In Windows Vista, UAC and its Admin Approval Mode are enabled by default. When UAC is enabled, local administrator accounts run as standard user accounts. This means that when a member of the local Administrators group logs on, they run with their administrative privileges disabled. This is the case until they attempt to run an application or task that has an administrative token. When a member of the local Administrators group attempts to start such an application or task, they are prompted to consent to running the application as elevated. Scenario 1 details the procedure to run an application or task as elevated one time.

Note
To perform the following procedure, you must be logged into a client computer as a member of the local administrators group. You cannot be logged in with the computer (or built-in) administrator account because Admin Approval Mode does not apply to this account. (The built-in administrator account is disabled on new installations of Windows Vista.)

1. Start an application that is likely to have been assigned an administrative token, such as Microsoft Windows Disk Cleanup. A User Account Control prompt is displayed.

2. Verify that the details presented match the request you initiated.

3. In the User Account Control dialog box, click Continue to start the application.

Scenario 2 is similar to the previous scenario in that you want to run an application or process as elevated with the administrator access token. However, in this scenario you want to run an application that has not been marked by the developer or identified by the operating system as an administrative application. Some applications, such as internal line-of-business applications or non-Microsoft products might require administrative rights but have not been identified as such. In this scenario, you mark an application to prompt user for consent, and if granted, run as an administrative application. The following procedure steps you through that process.

Note
To perform the following procedure, you must be logged into a client computer as a member of the local administrators group. You cannot be logged in with the computer (or built-in) administrator account because Admin Approval Mode does not apply to this account.

Important
This procedure cannot be used to prevent UAC from prompting for consent to run an administrative application.

1. Right-click an application that is not likely to have been assigned an administrative token, such as a word processing application.

2. Click Properties, and then select the Compatibility tab.

3. Under Privilege Level, select Run this program as an administrator, and then click OK.

   Note
   If the Run this program as an administrator option is unavailable, it means that the application is blocked from always running elevated, the application does not require administrative credentials to run, the application is part of the current version of Windows Vista, or you are not logged into the computer as an administrator.

Scenario 3 outlines some common tasks that local administrators perform during the set up and configuration of client computers running Windows Vista. The following procedures step you through the tasks of turning off UAC, disabling Admin Approval Mode, disabling UAC from prompting for credentials to install applications, and changing the elevation prompt behavior.

Important
Advanced configuration options for UAC are not available in Windows Vista Starter, Windows Vista Home Basic, or Windows Vista Home Premium.

Turning off UAC

Use the following procedure to disable UAC.

To perform the following procedure, you must be able to log on with or provide the credentials of a member of the local Administrators group.

Important
Turning off UAC reduces the security of your computer and may expose you to increased risk from malicious software. We do not recommend leaving UAC disabled.

To turn off UAC

1. Click Start, and then click Control Panel.

2. In Control Panel, click User Accounts.

3. In the User Accounts window, click User Accounts.

4. In the User Accounts tasks window, click Turn User Account Control on or off.

5. If UAC is currently configured in Admin Approval Mode, the User Account Control message appears. Click Continue.

6. Clear the Use User Account Control (UAC) to help protect your computer check box, and then click OK.

7. Click Restart Now to apply the change right away, or click Restart Later and close the User Accounts tasks window.

Disable Admin Approval Mode

Use the following procedure to disable Admin Approval Mode.

Note
To perform the following procedure, you must be logged into a client computer as a local administrator.

Important
You cannot disable Admin Approval Mode on Windows Vista Starter, Windows Vista Home Basic, or Windows Vista Home Premium because secpol.msc is not included.

To disable Admin Approval Mode

1. Click Start, click All Programs, click Accessories, click Run, type secpol.msc in the Open box, and then click OK.

2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue..

3. From the Local Security Settings console tree, double-click Local Policies, and then double-click Security Options.

4. Scroll down and double-click User Account Control: Run all administrators in Admin Approval Mode.

5. Select the Disabled option, and then click OK.

6. Close the Local Security Settings window.

Disable User Account Control from prompting for credentials to install applications

Use the following procedure to disable UAC from prompting for credentials to install applications.

Note
To perform the following procedure, you must be logged into a client computer as a local administrator.

Important
This procedure is not supported on Windows Vista Starter, Windows Vista Home Basic, or Windows Vista Home Premium.

To disable UAC from prompting for credentials to install applications

1. Click Start, click All Programs, click Accessories, click Run, type secpol.msc in the Open text box, and then click OK.

2. From the Local Security Settings console tree, click Local Policies, and then Security Options.

3. Scroll down and double-click User Account Control: Detect application installations and prompt for elevation.

4. Select the Disabled option, and then click OK.

5. Close the Local Security Settings window.

Change the elevation prompt behavior

Use the following procedures to change the elevation prompt behavior for UAC. You can configure the behavior of the elevation prompt separately for administrators and for standard users.

Note
To perform the following procedures, you must be logged on to a client computer as a local administrator.

Important
To complete the following procedures, you must be running Windows Vista Ultimate, Windows Vista Enterprise, or Windows Vista Business. You cannot complete the following procedures if you are running Windows Vista Starter, Windows Vista Home Basic, or Windows Vista Home Premium because secpol.msc is not included.

To change the elevation prompt behavior for administrators

1. Click Start, click Accessories, click Run, type secpol.msc in the Open box, and then click OK.

2. From the Local Security Settings console tree, click Local Policies, and then Security Options.

3. Scroll down to and double-click User Account Control: Behavior of the elevation prompt for administrators.

4. From the drop-down menu, select one of the following settings:

   • Elevate without prompting (tasks requesting elevation will automatically run as elevated without prompting the administrator)
     
     
   • Prompt for credentials (this setting requires user name and password input before an application or task will run as elevated)
     
     
   • Prompt for consent (default setting for administrators)
     
     

5. Click OK.

6. Close the Local Security Settings window.

To change the elevation prompt behavior for standard users

1. Click Start, click Accessories, click Run, type secpol.msc in the Open box, and then click OK.

2. From the Local Security Settings console tree, click Local Policies, and then Security Options.

3. Scroll down to and double-click User Account Control: Behavior of the elevation prompt for standard users.

4. From the drop-down menu, select one of the following settings:

   • Automatically deny elevation requests (standard users will not be able to run programs requiring elevation, and will not be prompted)
     
     
   • Prompt for credentials (this setting requires user name and password input before an application or task will run as elevated, and is the default for standard users)
     
     

5. Click OK.

6. Close the Local Security Settings window.

Since UAC is a feature of Windows Vista, support is available directly from Microsoft and from user communities. For information about support, see http://go.microsoft.com/fwlink/?LinkID=76619.

• For information about managing security and UAC in a business or enterprise environment, see the Windows Vista Security Guide (http://go.microsoft.com/fwlink/?LinkID=85735).