An ongoing spam campaign has been spotted using ISO disk image file attachments to disguise various information-stealing trojans, including LokiBot and NanoCore. Spam sent to victims claim to be a generic message about an invoice and include an ISO file as an attachment. An ISO file is an archive file that contains all the information that would be written to an optical disc. Once a victim clicks on the image, either the LokiBot or NanoCore trojan was then downloaded onto their system.
Source: https://threatpost.com/malspam-emails-blanket-lokibot-nanocore-malware-with-iso-files/145991/