Triggered by John Trozzi reporting a spoof email. Single-user check
confirmed him clean (reported, not compromised). Tenant-wide sweep
found a sustained ~1 month campaign from 4 external IPs (UA/US/DE/AT
- deltahost + ColoCrossing) plus a compromised-M365-tenant relay
vector. Deleted 14 messages (Groups A+B) per Mike's explicit
authorization. Preserved legitimate HR thread (HRPYDBRUN xlsx) and
user outbound forwards as evidence.
Recommendations in report: DMARC p=quarantine/reject for
cascadestucson.com (biggest leverage), TABL IP blocks, zoom.nl
URL block, Defender impersonation protection.
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Howard Enos
a92d2d3f2c