M365EXO-020: SMTP AUTH disabled organization-wide (MS.EXO.5.1)
- Plataforma
- Entra ID / M365
- Categoría
- Advanced Threat Protection
- Severidad
- High
- Pilar de Zero Trust
- Identity (peso 3)
- Fixtures de referencia
- 3
- Cobertura de ramas
- Observada: los fixtures prueban los veredictos que ejercitan
- Procedencia
- baseline
Qué comprueba
SCuBA MS.EXO.5.1 requires that SMTP AUTH be disabled. SMTP AUTH is a legacy submission protocol that authenticates with username and password and cannot enforce multi-factor authentication. Leaving it enabled as the tenant default gives attackers a path to send mail using stolen credentials while bypassing MFA and Conditional Access.
Valor recomendado
SMTP AUTH disabled as the organization default (SmtpClientAuthenticationDisabled = True), with per-mailbox exceptions only for documented service accounts
Remediación
Disable SMTP AUTH as the global default by setting SmtpClientAuthenticationDisabled to True on the transport configuration. Where a specific service account genuinely requires SMTP AUTH, enable it only on that individual mailbox and document the justification. Monitor sign-in telemetry for SMTP AUTH usage and migrate legacy applications to modern authentication.
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.5.1v1
- NIST SP 800-53
- IA-2
- MITRE ATT&CK
- T1078, T1110