Quote Originally Posted by inu11byte View Post
Well... How do malware developers do it? How do they compile a single executable that can run on all machines and all Windows versions?
They don't compile a single executable as far as I know. They usually trick you to download a Java-applet which can determine which platform you use and then load the platform-specific part in the background.

But you can't use for example a binary for the Windows platform on Linux or Mac (disregarding any emulator/virtual machine in between).

See also Cross-platform - Wikipedia, the free encyclopedia (Subsection "Binary software")
Bye, Andreas