User Account Control (UAC)

User Account Control (UAC) is a key part of Windows security. UAC reduces the risk of malware by limiting the ability of malicious code to execute with administrator privileges. This article describes how UAC works and how it interacts with the end-users.

The basics of how UAC works

With UAC, each application that requires the administrator access token must prompt the end user for consent. The only exception is the relationship that exists between parent and child processes. Child processes inherit the user's access token from the parent process. Both the parent and child processes, however, must have the same integrity level.

Windows protects processes by marking their integrity levels. Integrity levels are measurements of trust:

• A high integrity application is one that performs tasks that modify system data, such as a disk partitioning application
• A low integrity application is one that performs tasks that could potentially compromise the operating system, like as a Web browser

Applications with lower integrity levels can't modify data in applications with higher integrity levels. When a standard user attempts to run an app that requires an administrator access token, UAC requires that the user provides valid administrator credentials.

To better understand how UAC works, see this article from Microsoft.