Computer users running some form of Mac OS X are immune to this particular Trojan Horse since it is a DLL which only works within the Windows environment. However, that does not mean there will never been one that targets the Mac. As always, users should be highly suspicious of any attempts by 3rd party software to elevate privileges by throwing up a screen which requires you to re-authenticate as an administrator. Unless you are installing legitimate commercial software or merely changing System Preferences via your own initiation, you are not wise to grant credentials.