Описание тега uac

This tag is used for questions concerning the User Account Control (UAC) security feature of Windows Vista, Windows 7, 8 and higher. This feature, enabled by default, reduces the privilege level of an Administrator account to those of Limited User account. Because of this, many programs that worked in previous Windows versions do not work as expected in Windows Vista, Windows 7, 8 and higher.

With UAC, each user having admin rights would have split-token - one for regular usage and one for administrative usage. Regular token won't be able to have administrative permissions (such as changing system-time, or installing applications). Administrative token would have rights to do any administrative activity.

A process (and all its threads) would have either of these tokens, and they cannot change to another token (for e.g. from Regular to Admin). User has to respond to UAC prompt when opening Admin mode (elevated) application.

Programmers can specify if their programs to require admin (elevated) token so that OS will always attempt to launch the process with elevation. This information is put into EXE header itself.