When an app attempts to run with an administrator's full access token, Windows 10 or Windows 11 first analyzes the executable file to determine its publisher. Apps are first separated into three categories based on the file's publisher: Windows 10 or Windows 11, publisher verified signed , and publisher not verified unsigned. The following diagram illustrates how Windows determines which color elevation prompt to present to the user. Some Control Panel items, such as Date and Time Properties , contain a combination of administrator and standard user operations.
Standard users can view the clock and change the time zone, but a full administrator access token is required to change the local system time. The shield icon on the Change date and time button indicates that the process requires a full administrator access token and will display a UAC elevation prompt. The elevation process is further secured by directing the prompt to the secure desktop.
The consent and credential prompts are displayed on the secure desktop by default in Windows 10 and Windows Only Windows processes can access the secure desktop. For higher levels of security, we recommend keeping the User Account Control: Switch to the secure desktop when prompting for elevation policy setting enabled.
When an executable file requests elevation, the interactive desktop, also called the user desktop, is switched to the secure desktop. The secure desktop dims the user desktop and displays an elevation prompt that must be responded to before continuing. When the user clicks Yes or No , the desktop switches back to the user desktop. Malware can present an imitation of the secure desktop, but when the User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode policy setting is set to Prompt for consent , the malware does not gain elevation if the user clicks Yes on the imitation.
If the policy setting is set to Prompt for credentials , malware imitating the credential prompt may be able to gather the credentials from the user. However, the malware does not gain elevated privilege and the system has other protections that mitigate malware from taking control of the user interface even with a harvested password. While malware could present an imitation of the secure desktop, this issue cannot occur unless a user previously installed the malware on the PC.
Because processes requiring an administrator access token cannot silently install when UAC is enabled, the user must explicitly provide consent by clicking Yes or by providing administrator credentials. If the operation changes the file system or registry, Virtualization is called. All other operations call ShellExecute. ShellExecute calls CreateProcess. If it receives the error, ShellExecute calls the Application Information service to attempt to perform the requested task with the elevated prompt.
A system service that helps start apps that require one or more elevated privileges or user rights to run, such as local administrative tasks, and apps that require higher integrity levels. The Application Information service helps start such apps by creating a new process for the application with an administrative user's full access token when elevation is required and depending on Group Policy consent is given by the user to do so.
Notify me only when programs try to make changes to my computer do not dim my desktop will:. The User Account Control: Switch to the secure desktop when prompting for elevation policy setting is checked:. If the secure desktop is enabled, all elevation requests go to the secure desktop regardless of prompt behavior policy settings for administrators and standard users. If the secure desktop is not enabled, all elevation requests go to the interactive user's desktop, and the per-user settings for administrators and standard users are used.
CreateProcess calls AppCompat, Fusion, and Installer detection to assess if the app requires elevation. The file is then inspected to determine its requested execution level, which is stored in the application manifest for the file. The AppCompat database stores information in the application compatibility fix entries for an application.
The Fusion database stores information from application manifests that describe the applications. The manifest schema is updated to add a new requested execution level field. Installer detection detects setup files, which helps prevent installations from being run without the user's knowledge and consent.
Virtualization technology ensures that non-compliant apps do not silently fail to run or fail in a way that the cause cannot be determined.
UAC also provides file and registry virtualization and logging for applications that write to protected areas. The per-user file and registry virtualization redirects per-computer registry and file write requests to equivalent per-user locations. Read requests are redirected to the virtualized per-user location first and to the per-computer location second.
Because system administrators in enterprise environments attempt to secure systems, many line-of-business LOB applications are designed to use only a standard user access token. As a result, you do not need to replace the majority of apps when UAC is turned on. Windows 10 and Windows 11 include file and registry virtualization technology for apps that are not UAC-compliant and that require an administrator's access token to run correctly.
When an administrative apps that is not UAC-compliant attempts to write to a protected folder, such as Program Files, UAC gives the app its own virtualized view of the resource it is attempting to change. The virtualized copy is maintained in the user's profile. This strategy creates a separate copy of the virtualized file for each user that runs the non-compliant app.
Most app tasks operate properly by using virtualization features. The nature of User Account Control depends on the concept of developing multiple user accounts on an operating system, which began with Windows NT in Using User Account Control involves administering application requests, doing configuration and manually providing these specific status levels for users.
Microsoft has published guidelines for the use of User Account Control, and detailed tutorials online explain UAC settings as well as how to disable this feature on Windows operating systems. By: Justin Stoltzfus Contributor, Reviewer. By: Satish Balakrishnan. Dictionary Dictionary Term of the Day.
Natural Language Processing. Techopedia Terms. But, as mentioned before, writing to these directories requires elevated privileges! Unfortunately, ample workarounds are available. For one, the Windows Update Standalone Installer wusa.
But apparently a process may access its own handle and modify the flag PSAPI uses to assess its integrity level! So, the attack flow may be as follows:. For instance, it was discovered that when the fodhelper. And not just any values — but strings representing commands for execution! The relevant keys are:. Bear in mind that the user-hive registry values only require standard privileges to be edited, but the command will run in the context of an auto-elevating process.
There are currently at least 5 known unfixed key manipulation UAC bypasses. Instead of bypassing UAC by exploiting auto-elevation mechanisms, some exploits allow adversaries to disable UAC, either altogether or for a certain user or session. One famous vulnerability of this variety is CVE The exploit relies on a vulnerability in EasyInstall, also known as IXP, which is a remote desktop management tool used for managing endpoints and installing software over large networks.
Usually a central EasyInstall server will control agents installed on network endpoints. In the affected versions, the EasyInstall agent runs with admin privileges, but some of its folders were not write-protected.
Because the folders were not write-protected, the file could be replaced with a modified version flagging the agent to disable UAC. Upon rebooting the computer, UAC will be shut-down for all users until the machine was rebooted once again. First, we should be able to establish a Meterpreter session with the target machine. One approach for initial access using Meterpreter was demonstrated on our Office Macro Attacks article. The command failed, meaning the privileges could not be elevated.
After failing again, we pushed the session to the background and searched for UAC bypasses, which prompted many results:. Now we will demonstrate the use of two different bypasses. This payload, however, uses reflective DLL injection to minimize its footprint. The payload is used to elevate our background session. Notice the use of set target , set session and set payload to properly configure the exploit.
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