M365EXO-007: Auto-forwarding policy
- Plataforma
- Entra ID / M365
- Categoría
- Advanced Threat Protection
- Severidad
- Critical
- Pilar de Zero Trust
- Applications & Workloads (peso 2)
- Fixtures de referencia
- 3
- Cobertura de ramas
- Observada: los fixtures prueban los veredictos que ejercitan
- Procedencia
- baseline
Qué comprueba
Automatic email forwarding to external addresses is a common data exfiltration technique used by attackers after compromising a mailbox. An attacker can set up auto-forwarding rules to silently copy all incoming email to an external address, maintaining persistent access to sensitive communications even after their access is revoked. Organizations should block external auto-forwarding by default and audit any existing forwarding rules.
Valor recomendado
External auto-forwarding blocked via anti-spam outbound policy; existing forwarding rules audited and approved
Remediación
Configure the outbound spam filter policy to set automatic forwarding to 'Automatic - System-controlled' or 'Off' to block external auto-forwarding at the transport level. Audit all existing mailbox forwarding rules and SMTP forwarding configurations to identify any unauthorized external forwarding that may indicate compromise. Remove any unapproved forwarding rules and implement monitoring alerts to detect new forwarding rule creation using the unified audit log.
Veredictos probados con fixtures
Cada veredicto de esta tabla está probado por un fixture de referencia en la suite de pruebas que valida el módulo. La tabla se deriva de la última ejecución en verde; no puede editarse a mano.
| Escenario | Veredicto esperado |
|---|---|
| clean | PASS |
| known-bad | WARN |
| throttled | Not Assessed |
Mapeos a marcos de referencia
- CISA SCuBA
- MS.EXO.1.1v2
- NIST SP 800-53
- AC-4
- CIS M365 Benchmark
- 2.1.6
- MITRE ATT&CK
- T1114.003