M365EXO-013: Automatic forwarding to external domains disabled (MS.EXO.1.1)
- Plataforma
- Entra ID / M365
- Categoría
- Advanced Threat Protection
- Severidad
- High
- Pilar de Zero Trust
- Data (peso 2)
- Fixtures de referencia
- 3
- Cobertura de ramas
- Observada: los fixtures prueban los veredictos que ejercitan
- Procedencia
- baseline
Qué comprueba
SCuBA MS.EXO.1.1 requires that automatic forwarding to external domains be disabled. Remote domain configuration in Exchange Online governs whether mail can be auto-forwarded out of the tenant. When the default remote domain (*) permits auto-forwarding, a compromised mailbox can silently exfiltrate all inbound mail to an attacker-controlled external address, persisting access even after credentials are reset.
Valor recomendado
AutoForwardEnabled set to False on the default remote domain (*) and on every custom remote domain unless a specific partner integration is documented
Remediación
In the Exchange admin center under Mail flow, open Remote domains and edit the Default (*) entry so that automatic forwarding is not allowed (AutoForwardEnabled = False). Repeat for every custom remote domain that does not have a documented business need for cross-tenant auto-forwarding. Confirm the outbound spam policy auto-forward setting is consistent so that both control layers enforce the same restriction.
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 | FAIL |
| throttled | Not Assessed |
Mapeos a marcos de referencia
- CISA SCuBA
- MS.EXO.1.1v2
- NIST SP 800-53
- AC-4
- MITRE ATT&CK
- T1114.003