M365EXO-032: Impersonation protection checks enabled (MS.EXO.11.1)
- Platform
- Entra ID / M365
- Category
- Advanced Threat Protection
- Severity
- High
- Zero Trust pillar
- Applications & Workloads (weight 2)
- Golden fixtures
- 3
- Branch coverage
- Observed: fixtures prove the verdicts they exercise
- Provenance
- baseline
What it checks
SCuBA MS.EXO.11.1 recommends that impersonation protection checks be used. Impersonation protection compares sender addresses against known users and domains to flag look-alike addresses (for example, exmple.com versus example.com). Without it, users must manually distinguish near-identical sender addresses, which is unreliable and increases phishing success.
Recommended value
Anti-phish policy with user and/or domain impersonation protection enabled and applied to high-value targets
Remediation
Enable user and domain impersonation protection in an anti-phish policy and apply it to high-value targets such as executives, finance, and IT, plus organizational and key partner domains. Set the action for impersonated messages to quarantine. Note that impersonation protection requires a Defender for Office 365 plan; if unavailable, evaluate a comparable third-party capability.
Fixture-proven verdicts
Every verdict below is proven by a golden fixture in the module's gating test suite. This table derives from the last green run; it cannot be edited by hand.
| Scenario | Expected verdict |
|---|---|
| clean | PASS |
| known-bad | FAIL |
| throttled | Not Assessed |
Framework mappings
- NIST SP 800-53
- SI-8
- MITRE ATT&CK
- T1656, T1566