EIDAUTH-004: Users with Only SMS/Voice MFA Methods
- Platform
- Entra ID / M365
- Category
- Entra ID Authentication Methods & MFA
- Severity
- High
- Zero Trust pillar
- Identity (weight 2)
- Golden fixtures
- 3
- Branch coverage
- Observed: fixtures prove the verdicts they exercise
- Provenance
- baseline
What it checks
Users relying solely on SMS or voice-based MFA are vulnerable to SIM swap attacks, where attackers social-engineer mobile carriers to transfer a victim's phone number, and SS7 signaling protocol attacks that intercept SMS messages in transit. These methods provide significantly weaker protection than app-based or hardware token authentication. Organizations should identify and migrate these users to phishing-resistant methods.
Recommended value
No users relying exclusively on SMS or voice as their only MFA method
Remediation
Identify users with only SMS/voice MFA via Entra ID > Protection > Authentication methods > User registration details. Create a migration plan to move these users to Microsoft Authenticator or FIDO2 security keys. Consider disabling SMS/voice as allowed methods in the authentication methods policy after migration is complete.
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 | WARN |
| no-data | Not Assessed |
Framework mappings
- CISA SCuBA
- MS.AAD.3.5v2
- NIST SP 800-53
- IA-2(1)
- CIS M365 Benchmark
- 5.2.2.4
- MITRE ATT&CK
- T1111, T1078