The Australian Cyber Security Centre (ACSC) has released an advisory for widespread Emotet malware campaign which typically spreads thru infected email attachments.

https://www.us-cert.gov/ncas/current-activity/2019/10/25/acsc-releases-advisory-emotet-malware-campaign

 Emotet is a Trojan—commonly spread via malicious email attachments—that attempts to proliferate within a network by brute forcing user credentials and writing to shared drives.  Please see ACSC advisory and CISA’s Alert on Emotet Malware for more information.