M365EXO-017: DMARC policy published for each domain (MS.EXO.4.1)
- 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
SCuBA MS.EXO.4.1 requires that a DMARC policy be published for every second-level domain. DMARC is a DNS TXT record at _dmarc.<domain> that tells receivers how to handle mail failing SPF and DKIM and where to send reports. Without a DMARC record, receivers handle authentication failures inconsistently, allowing spoofed mail to reach inboxes.
Valor recomendado
A DMARC TXT record published at _dmarc for every second-level domain
Remediación
Publish a DMARC TXT record at _dmarc.<domain> for every second-level domain; a record at the second-level domain protects its subdomains. Begin with p=none to gather aggregate reports without affecting delivery, validate that legitimate sources align under SPF or DKIM, then progress the enforcement level. Confirm the record resolves correctly using a DNS lookup.
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.4.1v1
- NIST SP 800-53
- SI-8
- MITRE ATT&CK
- T1566.001