Oh Good, Our Calendars Are Malware Now

As if our meeting schedules were not depressing enough, HollowGraph malware now cleverly abuses compromised Microsoft 365 calendar accounts as two-way dead-drops for C&C communications. This delightfully annoying technique compromised organisations with 365 accounts who thought calendars were just for wasting time in meetings. Naturally, securing compromised Microsoft accounts and monitoring calendar abuse is how we attempt protection before hackers schedule their next intrusion.