Curated Cyber Threat Intelligence
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scheduleUpdated 2026-07-21 · 02:09 UTC
articleTotal: 606 reports
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HollowGraph malware abuses Microsoft 365 calendar for C2 and exfiltration
Microsoft 365 environments with compromised mailboxes. Threat actors leverage legitimate Microsoft Graph API and calendar features to establish covert command-and-control channels.
Microsoft15:43 UTC
highperson_alertThreat Actorperson_alertThreat Actor
HollowGraph malware uses Microsoft 365 calendars for covert C2
HollowGraph is a newly discovered espionage-focused malware family that employs a novel command and control mechanism leveraging compromised Microsoft 365 calendar infrastructure. The malware was identified and analyzed by Group-IB.
Microsoft12:33 UTC