The Emotet malware was considered the most widely spread malware in the past, using spam campaigns and malicious attachments to distribute the malware. Emotet would then use infected devices to perform other spam campaigns and install other payloads, such as the QakBot (Qbot) and Trickbot malware. These payloads would then be used to provide initial access to threat actors to deploy ransomware, including Ryuk, Conti, ProLock, Egregor, and many others.

Link: Emotet malware is back and rebuilding its botnet via TrickBot
via http://www.bleepingcomputer.com