Before you start
Objectives: learn how to configure User Account Control (UAC) feature in Vista
Prerequisites: you have to know what is UAC in Windows.
Key terms: user, uac, administrator, account, credentials, prompt, uac, token, privileges
When a user logs on to the system, an access token is generated for the user. The access token controls the type of actions that the user can perform on the system. The access token identifies the user account as either a standard user or an administrator. Certain actions can only be performed by a user with an administrator access token.
Let’s say that we log on to Windows Vista as a standard user and we try to install some application or edit some important system settings. Let’s go to Start, right-click Computer and then select Manage. We will get UAC prompt asking us to provide Admin password. The standard user token is used to attempt to perform all tasks for both standard users and administrators. If standard user rights are not sufficient to perform the task, the system requests privilege elevation. The standard user is prompted to provide administrator user credentials (username and password). This process is referred to as Prompt for credentials.
Image 231.1 – Admin Credentials
If we install some application with admin credentials, it does not mean that we can run it without admin credentials. Notice the window shield icon on the System Restore shortcut telling us that we are going to be prompted.
Image 231.2 – System Restore Icon
Any time we see that shield we will be prompted. Also, we are prompted for admin password every single time we use a particular piece of software. Instead of double-clicking the software we can also right-click it and select Run as Administrator. It is the same thing.
Image 231.3 – Run as Administrator
If we log on to Vista as an administrator, UAC acts a little bit differently. The difference when we are administrator is that we are prompted for consent and not for credentials. This is called Admin Approval Mode. The administrator user is asked whether the administrative token should be used to perform the task. Because the administrator has already logged on with the username and password, this is a simple Continue or Cancel question. This process is referred to as Prompt for consent.
Image 231.4 – Admin Approval Mode
In our case we tried to run System Configuration. All we have to do is click Continue. As administrators we still see the shield icon and we are prompted for credentials. This feature of UAC helps protect the system when an administrator user account is used by running all processes using the least administrative privileges necessary.
Prompting for credentials or consent activates the Secure Desktop. With the Secure Desktop, the Desktop and all active applications are darkened, and the prompt appears over the shaded desktop. We must respond to the prompt before we can continue with the requested operation or return to the desktop.
Turn UAC Off
UAC can be turned off, but it is not recommended. To turn it off we can go to Control Panel > User Accounts and Family Safety > User Accounts.
Image 231.5 – Admin User Account
Here we have an option to turn User Account Control on or off. If we turn it off here it will be turned off for all users on the machine.
We can change how UAC acts in our Local Group Policy. To open group policy editor enter ‘gpedit.msc’ in Run menu and hit Enter. Let’s go to Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options. Here we can find UAC options.
Image 231.6 – Security Options
We scrolled down to the bottom and we can see 9 different UAC settings. As administrators we can control the behavior of the elevation prompts for standard users and administrators. We can select, for example, to elevate without prompting or to only elevate files that are signed and validated.
UAC is a feature in Vista that helps minimize the dangers of unwanted actions or unintended software installations. We will see Prompt for credentials when a standard user tries to install some application or tries to edit some important system setting. If we log on as an administrator we will be prompted for consent and not for credentials. Prompting for credentials or consent activates the Secure Desktop which forces us to respond to the prompt. UAC can be turned off, and we can edit UAC behavior trough Group Policy.