American Dental Association given malware USB drives

From SC Magazine:

Malware embedded on a USB drive was delivered to members of the American Dental Association (ADA).

The mailing contained a PDF file of dental procedure codes, but some of the drives also held code capable of redirecting recipients to a website known to host malicious code. If a user opened the file, the site downloaded code that could enable miscreants to gain control of a user's Windows computer.