Suspicious MFA Fatigue via Repeated Denied Authentication Prompts (via signinlogs)

ATT&CK techniques

Cred Access

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
- T1621Multi-Factor Authentication Request Generation
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects Entra ID sign-in events where a multi-factor authentication prompt was denied or went unanswered by the user, the tell-tale event of an MFA fatigue or push-bombing campaign in which an adversary with valid credentials spams approval requests hoping the victim eventually accepts. MFA request generation is a growing identity technique in the Red Canary Threat Detection Report. Correlating repeated denied prompts for a user surfaces an in-progress account takeover.

Reporting behind it

Related detections9 linkedT1621 — drag to rearrange

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Suspicious MFA Fatigue via Repeated Denied Authentication Prompts (via signinlogs)

Pivot detection · T1621 · 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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