Every Windows user now knows about UAC, User Account Control setting introduced in Windows Vista pops up a dialog and seeks permission from administrator to allow running of a program that being tried to open, if you click on “Yes” button that program will run. By default all programs run at “medium integrity level” in Windows Vista/7, if you turn off UAC in Windows 7, all programs will run at “High Integrity level” which is not safe for e.g browser like Internet Explorer by default set to run at low integrity level, when UAC is disabled IE runs with high integrity which hackers and malicious programs can use to harm your Computer, that’s why it is not recommended to disable UAC on Windows. Things however changed and security is enhanced in Windows 8, you should know that if you disable UAC then all your applications will run at “Medium Integrity level”.
Windows 8 runs all Applications as Medium Integrity Process if you Disable UAC
To confirm this, all you’ve to do is download and run Sysinternals Process Explorer from Microsoft and from “View” menu “select columns” and check “Integrity”, see the Integrity column (also the last one) for changes when UAC is toggled from default to never notify position, you can see all programs running at Medium Integrity when UAC is off where in Windows 7 they run at high integrity level.
The above screenshot reflects the changes when UAC is turned off in Windows 8, you can see Snagit, Process Explorer, Firefox and Internet Explorer processes running at medium integrity. We came to know this change in Windows 8 via Mozilla’s brian bondy blog.