Adobe Reader is one of the most oft-used programs in the world. (Probably next to MS Word and other word processors.) And we all think it’s safe because it just reads a document format and displays it.
The attack vector is to send a poisoned PDF file to intended target individuals, purporting to be “From: a friend” and hoping that they’ll open the attached PDF thinking that it’s safe. Wrong again. You won’t be caught by this, will you?