Attackers used adversary-in-the-middle attacks to steal passwords, hijack sign-in sessions and skip authentication and then use victim mailboxes to launch BEC attacks against other targets.
Source: Healthcareitnews.com and Read More

FIN7 Deploys Anubis Backdoor to Hijack Windows Systems via Compromised SharePoint Sites
The Russian cybercrime group FIN7 is linked to a Python-based backdoor named Anubis, providing them remote access to compromised Windows systems, says Swiss cybersecurity firm