Malicious Business Email Compromise OAuth Application Sign-In via Entra ID Service Principal (via azure)

PremiumReviewedSigma · High · v1

Product: azure
Service: signinlogs
Author: HuntRule
Published: 2026-10-23
Updated: 2026-10-23

ATT&CK techniques

Initial Access → Defense Evasion

Recon
Resource Dev
Initial Access
- T1078.004Cloud Accounts
Execution
Persistence
- T1078.004Cloud Accounts
- T1098.002Additional Email Delegate Permissions
Priv Esc
- T1078.004Cloud Accounts
- T1098.002Additional Email Delegate Permissions
Defense Evasion
- T1078.004Cloud Accounts
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects Entra ID sign-ins tied to the PerfectData Software and eM Client OAuth application identifiers that Red Canary observed adversaries abusing to gain persistent mailbox access during business email compromise schemes. Attackers consent these third-party mail applications into a compromised tenant so they can read and exfiltrate mail through issued tokens without the victim password, making any sign-in with these application IDs a strong compromise indicator.

Reporting behind it

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Malicious Business Email Compromise OAuth Application Sign-In via Entra ID Service Principal (via azure)

Pivot detection · T1078.004 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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