The blockquote below is found here on page 12
The dropper component of Stuxnet is a wrapper program that contains all of the above components stored inside itself in a section name “stub”. This stub section is integral to the working of Stuxnet. When the threat is executed, the wrapper extracts the .dll file from the stub section, maps it into memory as a module, and calls one of the exports.
I am very new to IT-Security (and I know, that Stuxnet is maybe not the best place to start).
Sorry if this is a rash silly question.
NOTE: I don't have the required 300 reputation to set up own tags, which is why the tag list doesn't make any sense. If someone can edit the tags, I would suggest stuxnet, dropper or dropper-component, and advanced-persistent-threat