First-Contact External Teams Senders

This query lists external Microsoft Teams senders by the date they were first seen, surfacing recent first-contact senders.

Detection logic

Detection requirements

Platform: Identity Provider Linux macOS Office Suite SaaS Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
Log source product: microsoftthreatprotection
Log source service: messageevents

Detections can measure how the public catalogue is used — which detections people look for, and which pages bring them here. It sets a cookie that recognises this browser for 180 days. It is never linked to an account and never follows you to other sites. Privacy notice

Detection rules

First-Contact External Teams Senders

Detection logic

Detection requirements

MITRE ATT&CK mappings

From the source

Licence

Authorship

Detection rules