EIDTNT-003: Guest User Access Restrictions
- Platform
- Entra ID / M365
- Category
- Entra ID Tenant Configuration
- Severity
- High
- Zero Trust pillar
- Governance (weight 2)
- Golden fixtures
- 3
- Branch coverage
- Observed: fixtures prove the verdicts they exercise
- Provenance
- baseline
What it checks
Guest users are external identities invited to collaborate with the organization. By default, guest users may have overly broad visibility into the directory, including the ability to enumerate users, groups, and applications. Unrestricted guest access allows external parties to map the organization's identity structure, identify high-value targets, and gather intelligence for subsequent attacks. Guest permissions should be restricted to the minimum required for collaboration.
Recommended value
Guest user access restricted to properties and memberships of their own directory objects only
Remediation
Navigate to Entra ID > External Identities > External collaboration settings and review the guest user access restrictions. Set guest user access to the most restrictive option that limits guests to properties and memberships of their own directory objects. Verify that guests cannot enumerate the full user list, group memberships, or application registrations by testing with a guest account.
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 |
| no-data | Not Assessed |
Framework mappings
- CISA SCuBA
- MS.AAD.8.1v1
- NIST SP 800-53
- AC-14
- CIS M365 Benchmark
- 1.3.1
- MITRE ATT&CK
- T1078.004