M365EXO-010: External sender warnings
- Plataforma
- Entra ID / M365
- Categoría
- Advanced Threat Protection
- Severidad
- Medium
- Pilar de Zero Trust
- Applications & Workloads (peso 1)
- Fixtures de referencia
- 3
- Cobertura de ramas
- Observada: los fixtures prueban los veredictos que ejercitan
- Procedencia
- baseline
Qué comprueba
External sender identification helps users recognize when an email originates from outside the organization, reducing the effectiveness of impersonation and social engineering attacks. Without visible external sender indicators, users may not distinguish between internal colleagues and external senders spoofing internal display names. Configuring external sender tags or mail tips provides a visual cue that prompts users to exercise additional caution.
Valor recomendado
External sender tag or mail tip enabled to visually identify emails from external senders
Remediación
Enable the external sender identification feature in the Exchange Online anti-phishing policy to display a visual indicator on emails from external senders. Consider implementing a transport rule that prepends '[External]' to the subject line of inbound emails from outside the organization as an additional visual warning. Communicate the change to end users and provide guidance on how to identify and respond to suspicious external emails.
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.7.1v1
- NIST SP 800-53
- SI-8
- CIS M365 Benchmark
- 2.1.7