User Account Control


User Account Control is a mandatory access control enforcement feature introduced with Microsoft's Windows Vista and Windows Server 2008 operating systems, with a more relaxed version also present in the versions after Vista, being Windows 7, Windows Server 2008 R2, Windows 8, Windows Server 2012, Windows 8.1, Windows Server 2012 R2, Windows 10, and Windows 11. It aims to improve the security of Microsoft Windows by limiting application software to standard user privileges until an administrator authorises an increase or elevation. In this way, only applications trusted by the user may receive administrative privileges and malware are kept from compromising the operating system. In other words, a user account may have administrator privileges assigned to it, but applications that the user runs do not inherit those privileges unless they are approved beforehand or the user explicitly authorises it.
UAC uses Mandatory Integrity Control to isolate running processes with different privileges. To reduce the possibility of lower-privilege applications communicating with higher-privilege ones, another new technology, User Interface Privilege Isolation, is used in conjunction with User Account Control to isolate these processes from each other. One prominent use of this is Internet Explorer 7's "Protected Mode".
Operating systems on mainframes and on servers have differentiated between superusers and userland for decades. This had an obvious security component, but also an administrative component, in that it prevented users from accidentally changing system settings.
Early Microsoft home operating-systems did not have a concept of different user-accounts on the same machine. Subsequent versions of Windows and Microsoft applications encouraged the use of non-administrator user-logons, yet some applications continued to require administrator rights. Microsoft does not certify applications as Windows-compliant if they require administrator privileges; such applications may not use the Windows-compliant logo with their packaging.

Behavior in Windows versions

  • Windows 1.0x–3.11 and Windows 9x: all applications had privileges equivalent to the operating system;
  • All versions of Windows NT up to, and including, Windows XP and Windows Server 2003: introduced multiple user-accounts, but in practice most users continued to function as an administrator for their normal operations. Further, some applications would require that the user be an administrator for some or all of their functions to work.
  • Windows Vista and Windows Server 2008: Microsoft developed Vista security firstly from the Limited User Account, then renamed the concept to User Account Protection before finally shipping User Account Control. Introduced in Windows Vista, User Account Control offers an approach to encourage "super-user when necessary". The key to UAC lies in its ability to elevate privileges without changing the user context. As always, it is difficult to introduce new security features without breaking compatibility with existing applications.
  • *When someone logs into Vista as a standard user, the system sets up a logon session and assigns a token containing only the most basic privileges. In this way, the new logon session cannot make changes that would affect the entire system.
  • *When a person logs in as a user with membership in the Administrators group, the system assigns two separate tokens: the first token contains all privileges typically awarded to an administrator, and the second is a restricted token similar to what a standard user would receive.
  • **User applications, including the Windows Shell, then start with the restricted token, resulting in a reduced-privilege environment – even when running under an Administrator account.
  • **When an application requests higher privileges or when a user selects a "Run as administrator" option, UAC will prompt standard users to enter the credentials of an Administrator account and prompt Administrators for confirmation and, if consent is given, continue or start the process using an unrestricted token.
  • Windows 7 and Windows Server 2008 R2: Microsoft included a user interface to change User Account Control settings, and introduced one new notification mode: the default setting. By default, UAC does not prompt for consent when users make changes to Windows settings that require elevated permission through programs stored in %SystemRoot% and digitally signed by Microsoft. Programs that require permission to run still trigger a prompt. Other User Account Control settings that can be changed through the new UI could have been accessed through the registry in Windows Vista.
  • Windows 8/8.1 and Windows Server 2012/R2: add a design change. When UAC is triggered, all applications and the taskbar are hidden when the desktop is dimmed.
  • Windows 10 and Windows Server 2016-2022: early versions have the same layout as Windows 8 and 8.1. The Anniversary Update adds a more modern look, along with support for dark mode. Also, Windows 10 adds support for Windows Hello in the User Account Control dialog box.
  • Windows 11 and Windows Server 2025: has mostly the same layout as in later versions of Windows 10, but with visual changes that match the rest of the operating system's new look and feel.

    Tasks that trigger a UAC prompt

Tasks that require administrator privileges will trigger a UAC prompt ; they are typically marked by a security shield icon with the 4 colors of the Windows logo or with two panels yellow and two blue. In the case of executable files, the icon will have a security shield overlay. The following tasks require administrator privileges:
  • Running an Application as an Administrator
  • Changes to system-wide settings
  • Changes to files in folders that standard users don't have permissions for
  • Changes to an access control list, commonly referred to as file or folder permissions
  • Installing and uninstalling applications outside of:
  • *The %USERPROFILE% folder and its sub-folders.
  • **Most of the time this is in %APPDATA%., by default, this is a hidden folder.
  • ***Chrome's and Firefox's installer ask for admin rights during install, if given, Chrome will install in the Program Files folder and be usable for all users, if denied, Chrome will install in the %APPDATA% folder instead and only be usable by the current user.
  • *The Microsoft Store.
  • *The folder of the installer and its sub-folders.
  • **Steam installs its games in the /steamapps/ sub-folder, thus not prompting UAC. Some games require prerequisites to be installed, which may prompt UAC.
  • Installing device drivers
  • Installing ActiveX controls
  • Changing settings for Windows Firewall
  • Changing UAC settings
  • Configuring Windows Update
  • Adding or removing user accounts
  • Changing a user's account name or type
  • Turning on Guest account
  • Turning on network discovery, file and printer sharing, Public folder sharing, turning off password protected sharing or turning on media streaming
  • Configuring Parental Controls or Family Safety
  • Running Task Scheduler
  • Backing up and restoring folders and files
  • Merging and deleting network locations
  • Turning on or cleaning logging in Remote Access Preferences
  • Running Color Calibration
  • Changing remote, system protection or advanced system settings
  • Restoring backed-up system files
  • Viewing or changing another user's folders and files
  • Running Disk Defragmenter, System Restore or Windows Easy Transfer
  • Running Registry Editor
  • Running the Windows Experience Index assessment
  • Troubleshoot audio recording and playing, hardware / devices and power use
  • Change power settings, turning off Windows features, uninstall, change or repair a program
  • Change date and time and synchronizing with an Internet time server
  • Installing and uninstalling display languages
  • Change Ease of Access administrative settings
Common tasks, such as changing the time zone, do not require administrator privileges. A number of tasks that required administrator privileges in earlier versions of Windows, such as installing critical Windows updates, no longer require administrator privileges in Vista. Any program can be run as administrator by right-clicking its icon and clicking "Run as administrator", except MSI or MSU packages as, due to their nature, if administrator rights will be required a prompt will usually be shown. Should this fail, the only workaround is to run a Command Prompt as an administrator and launch the MSI or MSP package from there.

Features

User Account Control asks for credentials in a Secure Desktop mode, where the entire screen is temporarily dimmed, Windows Aero disabled, and only the authorization window at full brightness, to present only the elevation user interface. Normal applications cannot interact with the Secure Desktop. This helps prevent spoofing, such as overlaying different text or graphics on top of the elevation request, or tweaking the mouse pointer to click the confirmation button when that's not what the user intended. If an administrative activity comes from a minimized application, the secure desktop request will also be minimized so as to prevent the focus from being lost. It is possible to disable Secure Desktop, though this is inadvisable from a security perspective.
In earlier versions of Windows, Applications written with the assumption that the user will be running with administrator privileges experienced problems when run from limited user accounts, often because they attempted to write to machine-wide or system directories or registry keys. UAC attempts to alleviate this using File and Registry Virtualization, which redirects writes to a per-user location within the user's profile. For example, if an application attempts to write to a directory such as "C:\Program Files\appname\settings.ini" to which the user does not have write permission, the write will be redirected to "C:\Users\username\AppData\Local\VirtualStore\Program Files\appname\settings.ini". The redirection feature is only provided for non-elevated 32-bit applications, and only if they do not include a manifest that requests specific privileges.
There are a number of configurable UAC settings. It is possible to:
  • Require administrators to re-enter their password for heightened security,
  • Require the user to press Ctrl+Alt+Del as part of the authentication process for heightened security;
  • Disable only file and registry virtualization
  • Disable Admin Approval Mode entirely; note that, while this disables the UAC confirmation dialogs, it does not disable Windows' built-in LUA feature, which means that users, even those marked as administrators, are still limited users with no true administrative access.
Command Prompt windows that are running elevated will prefix the title of the window with the word "Administrator", so that a user can discern which instances are running with elevated privileges.
A distinction is made between elevation requests from a signed executable and an unsigned executable; and if the former, whether the publisher is 'Windows Vista'. The color, icon, and wording of the prompts are different in each case; for example, attempting to convey a greater sense of warning if the executable is unsigned than if not.
Internet Explorer 7's "Protected Mode" feature uses UAC to run with a 'low' integrity level. As such, it effectively runs in a sandbox, unable to write to most of the system without elevating via UAC. Since toolbars and ActiveX controls run within the Internet Explorer process, they will run with low privileges as well, and will be severely limited in what damage they can do to the system.