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Threat actor

LYCEUM

Tracked by CyberSIXT since Jul 20, 2026 · last activity Jul 20, 2026

Linked incidents

malware open 2 articles

HollowGraph malware exploits Microsoft 365 calendars for covert C2

Coverage timeline

HOLLOWGRAPH Malware Hides Command-and-Control in Microsoft 365 Calendars
securityonline.info · Jul 20, 2026