From securityweek.com
Researchers have discovered a functionality within Office 365 that could allow attackers to ransom files stored on SharePoint and OneDrive. On disclosure to Microsoft, the researchers were told the system ‘is working as intended’. That is, it’s a feature, not a flaw.
It has long been considered that files stored and edited in the cloud are resilient to encryption extortion – the autosave and versioning features should provide sufficient backup capability.