CTI · corroborated · 2026-09-04

Hackers Bypass Microsoft 365 RejectDirectSend With Empty SMTP Sender to Spoof Internal Emails

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MITRE ATT&CK

• T1566 Phishing Initial Access
• T1571 Non-Standard Port Command and Control

Indicators

No curated indicators tied to this case.

Detections

No detection content yet — case analysis did not yield signal-specific telemetry. Check back after the next daily CTI pass.

References

• https://cyberpress.org
• https://gbhackers.com