Read this as an "introduction" and then you'll be able to understand why the researchers can be so sure that specific kind of malware must be state sponsored:

Read this as an "introduction" and then you'll be able to understand why the researchers can be so sure that specific kind of malware must be state sponsored: http://www.nytimes.com/2012/06/01/world/middleeast/obama-ordered-wave-of-cyberattacks-against-iran.html http://www.nytimes.com/2012/06/01/world/middleeast/obama-ord... http://www.langner.com/en/wp-content/uploads/2013/11/To-kill-a-centrifuge.pdf http://www.langner.com/en/wp-content/uploads/2013/11/To-kill... Simply, the goals ant he methods of the commercial malware are fundamentally different to those that can be recognized in the state-sponsored malware.