Microsoft Office 365 Corporate Users Hit by Cerber Ransomware Attack

A wave of spam emails carrying malicious file attachments infected with the Cerber ransomware hit corporate users of the Microsoft Office 365 service.

The onslaught began on June 22, just before 7:00 AM UTC, when crooks used a novel trick to launch Cerber-infested spam past Microsoft's security defenses.

Cloud security platform Avanan says it took Microsoft about a day to detect and start blocking the malicious file attachments.

By that point, it was too late, with Avanan saying that 57 percent of all companies using Office 365 had received at least one copy of the ransomware in their inboxes.

There is nothing special about this version of Cerber, and this seems to be yet another case of crooks managing to bypass Microsoft's spam filters. A similar incident happened on June 1, when hackers