Forest trust SID filtering vs SID history — are these the same setting or two different things?
Working through an AD security finding in an isolated lab and want a sanity check on my understanding before I take this to a client.
The finding: "Domain trust to a third-party domain without quarantine" (ANSSI vuln1_trusts_domain_notfiltered). Description says it looks for outbound forest trusts where the Quarantine flag is false, meaning the trusted domain isn't subject to SID filtering.
What I did in the lab:
Built two forests, forestA.local and forestB.local, and created an outbound forest trust from A (B trusts A, so A's users can be authorized in B).
Scanned it — passed clean. Trust attributes read:
Direction : Outbound
ForestTransitive : True
SIDFilteringForestAware : False
SIDFilteringQuarantined : False
I'd expected SIDFilteringQuarantined : False to fire the finding, but it didn't. My read is that quarantine isn't the active control on a forest trust, so False there is the normal secure default. Is that right?
Then I ran:
netdom trust forestA.local /domain:forestB.local /EnableSIDHistory:Yes
Re-scanned — finding fired. Trust attributes now showed 72 [TRUST_ATTRIBUTE_TREAT_AS_EXTERNAL, TRUST_ATTRIBUTE_FOREST_TRANSITIVE]. Quarantine never changed; only SID history did.
Where I'm confused:
- Is "enabling SID history" and "disabling SID filtering" the same change described two ways, or are they genuinely separate controls? My current understanding is that on a forest trust there's no independent filtering switch — allowing SID history is how filtering gets relaxed. Correct?
- Am I right that the switch differs by trust type? Forest trust →
/EnableSIDHistory, external trust →/Quarantine. Same underlying protection, different lever depending on type. - The scanner's result line says "Quarantine is disabled or SID history is enabled" — so two independent trigger conditions, either one alone fires it. Does that match how you'd read it?
Why it matters: I need to phrase this correctly in a client report. My current wording is:
>
Does that hold up, or am I conflating things?
Also — practical question — has anyone hit a case where disabling SID history broke legitimate cross-forest access? Trying to work out what to ask a client before remediating, since I assume an in-flight migration is the one genuine reason it'd be on.