M365EXO-041: URL block-list comparison enabled (MS.EXO.15.1)
- 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.15.1 recommends that URL comparison with a block list be enabled. Time-of-click URL protection compares links against block lists and known-malicious site lists so users are stopped before reaching dangerous destinations. Without it, links that are weaponized after delivery remain clickable and unprotected.
Recommended value
Safe Links (or comparable) policy enabled for email with URL scanning active (EnableSafeLinksForEmail = True)
Remediation
Enable a Safe Links or comparable URL protection policy for email so links are scanned against block lists and known-malicious site lists at time of click. Apply the policy to all users and avoid broad do-not-rewrite URL exceptions. Safe Links requires a Defender for Office 365 plan; where unavailable, evaluate a comparable third-party link protection 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-3
- MITRE ATT&CK
- T1566.002