Is Exchange Online Threatened by Ransomware?

The question of whether ransomware could infect and encrypt an Exchange Online mailbox raised by Michael Van Horenbeeck is fair. Although no reports exist of such an infection, the tools are there and, no doubt, someone is willing to try such an attack. Vendors of cloud backup solutions like to raise this point with potential customers. They argue that Microsoft’s strategy of using Native Data Protection to avoid the need for backups of Exchange Online mailboxes is insufficient in a world where deliberate acts of malfeasance, such as ransomware attacks, are well known.