The vast majority of attacks like these have target Windows via exploits in Word.

FORBES: First-Known Targeted Malware Attack On Android Phones Steals Contacts And Text Messages

In a preview of its presentation, the team acknowledges Apple's "plethora of defense mechanisms in iOS." Historically, Mac users have been able to boast of being largely malware free, in part because spammers, scammers and hackers preferred to target the larger number of Windows computers in the world.

CNN: Doug Gross,

Furthermore, Windows is the preferred target for computer viruses.

ECONOMIST: Software