Plan
archived
HollowGraph malware abuses M365 calendar as C2 channel
- Engineer — Learn: Novel living-off-the-land C2 technique abusing legitimate Microsoft Graph calendar APIs to blend into normal M365 traffic; no patch exists but worth reviewing M365 conditional-access and app-permission scopes to limit blast radius of compromised accounts.
- SOC/IR — Plan: Build or tune detection for anomalous Graph API calendar activity (unexpected event creation, unusual read patterns from non-user agents) in M365 audit logs; no published IOCs yet, but the TTP is concrete enough to start a detection rule in Sentinel or Elastic against Graph audit data.
- Leader — Learn: Illustrates how attackers leverage licensed SaaS infrastructure to evade network-level controls; useful context for future budget conversations around M365 audit-log retention and cloud SIEM coverage, but no immediate leadership action required.
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