Identity-Provider Recon — Tenant, Federation & User-Enumeration Oracle Mapping

Companion skills: osint-methodology (§6.2 detectability tagging, §11 identity-fabric pointer — the "how to think" skill this plugs into) and offensive-osint (§22 Identity Fabric — the concrete endpoint/payload reference this skill builds a workflow on top of, rather than re-listing). This skill answers the question those two don't: how do the tenant, its federation partners, its IdP, and its user-enumeration oracle fit together as one map — and where exactly enumeration stops and credential submission begins.

0. When to Use / When NOT

Use this skill when:

• You need to resolve a domain to its identity tenant (Entra/Okta/ADFS/Google Workspace) and determine whether auth is Managed or Federated.
• You need to map an org's federation boundary — every sibling domain that shares the same M365/Azure AD tenant trust, not just the seed.
• You need to distinguish Entra vs. Okta vs. ADFS vs. Google Workspace vs. a generic OIDC IdP from passive/low-detectability signals.
• You need to detect Seamless SSO or Microsoft Defender for Identity (MDI) presence — both change the risk calculus of anything downstream.
• You have authorization for a Medium-detectability, log-generating pass and need to run a pre-auth user-enumeration oracle (GetCredentialType / Okta /api/v1/authn) to build a valid-account list — without ever submitting a password.
• You have harvested employee names and a confirmed org email-format pattern and need to synthesize ranked login candidates to feed that oracle.

Do NOT use this skill when:

• You need to submit credentials, replay breach creds, forge/replay a token, or confirm an auth-bypass — that is a different, higher-authorization tier. See §14.
• The target's authorization for active, logged probing isn't established — the passive half of this skill (§7–§10) needs the same soft-scope posture as every companion skill; the active half (§11) needs it explicitly, because it generates tenant-side audit-log events (§1, §11.4).
• You already have concrete endpoints and just need the reference table — go straight to offensive-osint §22.

1. Authorization & Legal Posture

Same base posture as osint-methodology §1: intended for assets the operator owns or has written authorization to assess.

This skill carries a sharper posture than most of the pack because §11 is not passive. Every domain-resolution, federation, IdP-fingerprint, Seamless-SSO, and MDI probe in §7–§10 is Low detectability (a metadata GET/POST that any browser makes) — but the user-enumeration oracle in §11 is Medium detectability: it is a targeted, per-account POST against a live authentication endpoint, and both Microsoft and Okta log it in the tenant's own sign-in/audit trail. Treat §7–§10 and §11 as two separate authorization tiers even within one engagement.

Soft scope check — ask once before running §11:

"I can build a valid-account list by probing Microsoft/Okta's pre-auth user-existence oracle. This never submits a password, but it IS logged in the tenant's own audit trail and is rate-limited on my end to stay under the radar. Confirm you want me to run this active pass?"

Always-on guardrails specific to this skill:

• Never submit a real password, a guessed password, or any credential to any login endpoint. §11's oracles work by reading the shape of a rejection (§11.2, §11.3), not by trying to succeed.
• Cap user-enumeration at 20 candidates per tenant (§11.4) — this is not a suggestion, it is the production cap in the module this skill is grounded in.
• A discover_only federated sibling domain (§8) is a lead, never a target. Confirm ownership before extending §7–§11 to it.
• Nothing in this skill authorizes §14's excluded techniques, no matter how interesting the oracle results look.

2. Confidence Levels

Same three-tier model as the companion skills, applied to identity-fabric assertions:

Rule of three still applies to anything you'd report as organizational fact ("this org uses Entra") beyond a single tenant-level metadata hit — a single OIDC response is enough to say "an Entra tenant answers for this domain," but attributing that tenant to a specific subsidiary or brand needs the same corroboration discipline as org-attack-surface §2.

3. Output Format

Standard Finding schema (companion skill §3), with category: SSO_EXPOSURE for every identity-fabric finding in this skill — that is the category the reference implementation this skill is grounded in uses uniformly, from an INFO tenant-identified breadcrumb through a LOW confirmed-user-enumeration result:

Finding:
  id:          <stable hash>
  module:      identity-provider-recon
  asset_key:   svc:0.0.0.0:443:<product>      # tenant SERVICE asset key pattern — see §7.9
  category:    SSO_EXPOSURE
  severity:    <info|low|medium|high|critical>   # see per-section severity notes below
  confidence:  <tentative|firm|confirmed>
  title:       <one-line summary>
  description: <2-5 sentences>
  evidence:
    url:               <probe endpoint hit>
    timestamp:         <UTC ISO8601>
    discovery_method:  <oidc_metadata|getuserrealm|autodiscover|okta_oidc|adfs|saml_metadata|
                         workspace_mx|mx_inference|tenant_federation|seamless_sso|mdi_presence|
                         user_enum_microsoft|user_enum_okta>
    tenant_id:         <GUID / org slug / entity_id, when known>
  references:  [<AADInternals, MITRE ATT&CK technique, vendor doc>]
  remediation: <action the tenant owner can take>

UTC timestamps everywhere. For §11 oracle results specifically, the evidence block MUST carry probed_count, the enumerated address list(s) split by outcome, and — critically — a credential_submitted: false marker, so a downstream reader (or auditor) can never mistake an enumeration result for a proven-live credential.

4. Source Hygiene & Citations

Same discipline as the companion skills: URL + UTC timestamp + tool version + run_id on every artifact.

• Record the exact request body sent to GetCredentialType / Okta authn, not just "I probed the endpoint" — the oracle's entire evidentiary value is in the response differential, which is worthless without the paired request.
• Cache raw SOAP/JSON responses from GetFederationInformation, OIDC metadata, and getuserrealm.srf — these are the primary evidence for the tenant-federation map and should survive a re-run months later even if the live tenant configuration has since changed.
• Never log a probed password value in any artifact, even the fixed placeholder Okta's authn oracle requires (§11.3) — redact it in stored evidence as <oracle-placeholder>.

5. Do NOT

• Do NOT submit a real, guessed, or breach-sourced password to any login endpoint under this skill. §11's oracles are read-only-by-design: Microsoft's GetCredentialType and Okta's /api/v1/authn both reveal account existence from the shape of a rejection, never from a successful login.
• Do NOT exceed the 20-candidate-per-tenant cap on user enumeration (§11.4).
• Do NOT auto-promote a discover_only federated sibling domain (§8) into active scope. Confirm ownership first.
• Do NOT treat a STRONG-looking Okta-org-slug guess as confirmed until its own OIDC metadata answers and its issuer field actually contains okta.com (§7.4) — a guessed slug that happens to resolve to someone else's Okta org is a namesake collision, not a hit.
• Do NOT synthesize login candidates from names without a confirmed org email pattern (§12.2) — return nothing rather than spray 8 unverified permutations per name at a live oracle.
• Do NOT run §11 (the active oracle) without the sharper authorization posture in §1.
• Do NOT proceed past §11 into password spray, credential replay, or auth-bypass confirmation — that is explicitly out of scope everywhere in this skill (§14).

6. The Identity-Fabric Map — Mental Model

Most identity recon stops at "what login page does this domain redirect to." That single fact misses everything this skill is built to surface: the tenant boundary, who else federates into it, what defensive posture it runs, and — under explicit authorization — which specific accounts on it are real.

        ┌─────────────────────────────┐
        │   DOMAIN → TENANT             │   §7 — getuserrealm.srf, Entra OIDC metadata,
        │   (who owns the login?)        │        Autodiscover v2, Okta org-slug + OIDC,
        └──────────────┬───────────────┘        ADFS fingerprint, Google Workspace MX,
                        │                        generic OIDC, SAML metadata
                        ▼
        ┌─────────────────────────────┐
        │   FEDERATION MAP               │   §8 — GetFederationInformation SOAP:
        │   (who else shares this trust?)│        every sibling domain in the SAME
        └──────────────┬───────────────┘        M365/Azure AD tenant, discover-only
                        │
                        ▼
        ┌─────────────────────────────┐
        │   IdP POSTURE                  │   §9 distinguishing signals + §10 —
        │   (Managed/Federated, Seamless │        Seamless SSO Negotiate challenge,
        │   SSO, MDI monitoring)         │        MDI sensor-API presence
        └──────────────┬───────────────┘
                        │  authorization gate — §1 tightens here
                        ▼
        ┌─────────────────────────────┐
        │   CANDIDATE SYNTHESIS          │   §12 — harvested names x CONFIRMED org
        │   (who do we probe?)           │        pattern → ranked login candidates,
        └──────────────┬───────────────┘        fail-closed with no pattern
                        │
                        ▼
        ┌─────────────────────────────┐
        │   USER-ENUMERATION ORACLE      │   §11 — GetCredentialType / Okta authn,
        │   (which accounts are real?)   │        valid-account list OUTPUT, capped
        └──────────────┬───────────────┘        at 20/tenant, never a password sent
                        │
                        ▼            ← THE HARD BOUNDARY (§14) —
              [ everything below      spray / credential submission / auth bypass
                this line is OUT      is a different authorization tier entirely
                of this skill's       and lives in the engagement's authenticated-
                scope ]               testing phase, not here.

Every stage feeds the next. A tenant you can't resolve (§7) has no federation map to walk (§8). A federation map with no confirmed tenant SERVICE asset gives §11 nothing to enumerate against — the production implementation this skill is grounded in gates the oracle specifically on tenants that were resolved via oidc_metadata, getuserrealm, autodiscover, or okta_oidc (§7.9), not on a bare domain guess.

7. Domain → Tenant Resolution

Six independent probes, all Low detectability, run concurrently against the same seed domain. Any one confirms tenant existence; running all of them cross-corroborates and often fills in fields a single probe leaves blank (e.g. getuserrealm confirms Federated but not the tenant GUID; OIDC metadata fills that in separately).

7.1 Microsoft — getuserrealm.srf (Managed vs. Federated)

GET https://login.microsoftonline.com/getuserrealm.srf?login={probe-user}@{domain}&xml=1

Needs one plausible username local-part — use a harvested email if you have one, else a synthetic admin@{domain} seed (this is a Microsoft-side probe; it never touches the client's own infra). Cheap regex-extract the response fields rather than pulling in a full XML parser:

D="target.example"; U="admin"
curl -sk -m 15 "https://login.microsoftonline.com/getuserrealm.srf?login=${U}@${D}&xml=1"

$D = "target.example"; $U = "admin"
Invoke-RestMethod -Uri "https://login.microsoftonline.com/getuserrealm.srf?login=$U@$D&xml=1"

Response fields: NameSpaceType (Managed / Federated / Unknown — Unknown means Microsoft has no record of the domain, stop here), FederationBrandName, AuthURL (present only when Federated — the upstream ADFS/IdP URL), CloudInstanceName.

Why Managed vs. Federated matters for everything downstream: Managed means authentication terminates directly at login.microsoftonline.com — no on-prem ADFS proxy sits in front of it, so §11's GetCredentialType oracle and any later authenticated-testing phase hit Entra's own (more permissive) IP-based throttling with no ADFS Extranet Lockout buffer. Federated routes through whatever AuthURL points to (usually ADFS — cross-reference §7.5). Severity note: a Managed namespace on its own is a MEDIUM SSO_EXPOSURE finding (spray/MFA-fatigue hits Entra with no ADFS buffer), FIRM confidence — it is a posture fact, not a vulnerability, but it changes risk on everything that follows.

7.2 Microsoft Entra (Azure AD) — OIDC metadata + tenant GUID

GET https://login.microsoftonline.com/{domain}/.well-known/openid-configuration

issuer (and token_endpoint) contain the tenant GUID:

\b[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\b

A hit here is CONFIRMED confidence, INFO severity — it's the federation root every downstream SaaS integration trusts, not a weakness by itself, but the single most valuable pivot anchor in the whole identity fabric (a leaked credential + this tenant GUID = a pre-auth pivot into every federated SaaS).

7.3 Autodiscover v2 (Exchange Online / M365 mailbox confirmation)

GET https://autodiscover-s.outlook.com/autodiscover/autodiscover.json/v1.0/{email}?Protocol=Autodiscoverv1

Needs a probe email (harvested, or synthetic admin@{domain}). A response containing a Protocol or Url field confirms the mailbox — and therefore the M365 tenant — exists. FIRM confidence, no finding by itself (feeds the tenant SERVICE node); this is a corroboration probe, not a standalone signal.

Autodiscover IP correlation (companion skill offensive-osint §22.1) is a complementary passive check when MX is masked by an inbound filter (Mimecast/Proofpoint/Barracuda) — resolve autodiscover.{domain} and check whether it lands in Exchange Online IP space. Use it alongside this probe, not instead of it.

7.4 Okta — org-slug derivation + OIDC fingerprint + governed domains

Okta has no domain-keyed discovery endpoint the way Microsoft does — you derive candidate org slugs and confirm each by fetching its OIDC config.

Candidate derivation (from the target's own domain stem + any subdomain that is literally an *.okta.com host already in your graph):

candidates = { stem, stem-prod, stem-dev, stemcorp, stem-corp } ∪ { okta-slug matches in known subdomains }

[a-z0-9][a-z0-9-]{1,40}\.okta\.com

Confirmation probe (Low detectability — Okta's own public metadata endpoint):

GET https://{slug}.okta.com/.well-known/openid-configuration

Only treat a slug as CONFIRMED when issuer actually contains okta.com — a slug guess that resolves to a different company's Okta org (namesake collision) is common with short/generic stems; don't attribute it without this check (§5). Distinguish Classic vs. OIE (Okta Identity Engine) by whether the issuer contains /oauth2/ — this affects which downstream endpoints and policies apply.

Governed custom domains (call ONLY after the org slug is confirmed real — never on a guess):

GET https://{slug}.okta.com/api/v1/domains

Returns every custom domain the org has verified as an identity-provider surface ({"domain": "...", "validationStatus": "VERIFIED"}). This is the Okta equivalent of §8's federation map — it reveals which branded login portals (login.acmecorp.com, sso.subsidiary.com) all route into the same Okta tenant, closing the "co-federation via a non-Microsoft IdP" gap that §8's Microsoft-only federation probe structurally cannot see. Each verified domain is a genuine tenant-map node, not a guess — emit it as its own domain asset governed by this Okta org.

7.5 ADFS — passive fingerprint + version + mex (active)

Passive fingerprint:

GET https://adfs.{domain}/adfs/ls/idpinitiatedsignon.aspx

A response body is version-fingerprintable from resource-reference strings: adfs/portal/css/style.css 2012 → ADFS 2012 R2 (3.0); adfs/portal/illustration/illustration.png → ADFS 2016/2019 (4.x/5.x); bare federation service string with neither marker → ADFS confirmed, version unknown. Severity: 2012 R2/3.0 → MEDIUM (weak-crypto defaults, historical golden-SAML entry point); newer/unknown → INFO.

Mex endpoint (active — this one logs on the target side, unlike the fingerprint GET above):

GET https://adfs.{domain}/adfs/services/trust/mex

A response containing wsdl:definitions confirms the mex endpoint is live and leaks federation metadata (endpoint URLs, signing certs, supported claim types). Gate this probe on the passive fingerprint already having confirmed ADFS — don't fire it speculatively.

7.6 Google Workspace — MX-correlated detection

Google Workspace has no per-tenant OIDC endpoint — accounts.google.com's /.well-known/openid-configuration is provider-wide, not tenant-specific, so it cannot confirm this specific domain is a Workspace customer on its own. Detection therefore hinges on MX:

dig +short MX target.example

Resolve-DnsName -Name target.example -Type MX

Any MX host containing aspmx.l.google.com or googlemail.com confirms Google Workspace. Emit the tenant node with tenant_id = domain (there is no separate tenant GUID to extract) and issuer = https://accounts.google.com for consistency with the other tenant nodes, but be explicit in the evidence block that the corroborating signal is MX, not a tenant-scoped metadata response.

7.7 Generic OIDC — Auth0 / Keycloak / Ping Identity / OneLogin / Duo

Probe /.well-known/openid-configuration on the target apex and on subdomains matching the common IdP-prefix set (auth, login, sso, idp, iam, identity, accounts, oauth) — both discovered subdomains that match and the fixed prefix list applied directly to the root domain, capped around 40 candidate hosts. Skip any hit already attributed to Microsoft/Okta/Google (issuer contains microsoftonline, okta.com, or accounts.google.com) — those are covered by the dedicated probes above.

7.8 SAML metadata discovery

Same host candidate set as §7.7 (apex + IdP-prefix subdomains), probed against 5 conventional metadata paths:

/saml/metadata
/FederationMetadata/2007-06/FederationMetadata.xml
/federationmetadata/2007-06/federationmetadata.xml
/simplesaml/saml2/idp/metadata.php
/auth/saml2/metadata

Structural confirmation (don't bother parsing full XML): body contains entitydescriptor or entitiesdescriptor (case-insensitive). Extract entityID via a simple attribute regex:

entityid=["']([^"']+)["']

Severity note: public SAML metadata is INFO, CONFIRMED — and the remediation is explicitly not "block this." Publishing SP↔IdP trust metadata is conventional; the risk is entirely in signing-key compromise, which this passive probe cannot assess. Don't over-call a routine metadata endpoint as a finding worth escalating.

7.9 Assembling the tenant SERVICE node

Every probe above upserts into the same tenant node when they resolve to the same product — merge, don't fragment, on (placeholder-IP, port 443, product) so "Microsoft Entra (Azure AD)" discovered via OIDC metadata AND via getuserrealm.srf AND via MX inference lands as one node with accumulating attrs and sources, not three disconnected fragments. Attach a domain OWNED_BY tenant edge. Track which discovery_method values are considered strong enough to gate §11's oracle downstream: oidc_metadata, getuserrealm, autodiscover, okta_oidc — a tenant node that only ever got an mx_inference hit (Google Workspace's usual path, or a weak Microsoft breadcrumb) should not, by itself, authorize spending oracle budget against it without at least one of the four stronger methods also confirming.

8. Federation Mapping — the Tenant Boundary

Domain resolution (§7) tells you a tenant exists. It says nothing about who else shares that same trust. This is the highest-value, most commonly skipped step in identity-fabric recon: an attacker who compromises credentials on any domain inside the federation boundary can pivot across all of them, because they share one authentication trust — but inward DNS/CT enumeration of the seed alone never surfaces sibling roots with no DNS trail back to it.

8.1 GetFederationInformation — the one keyless, Microsoft-only federation-map endpoint

A single unauthenticated SOAP POST to Microsoft's own infrastructure returns every domain federated into the same Azure AD / M365 tenant as the seed:

POST https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc
SOAPAction: "http://schemas.microsoft.com/exchange/2010/Autodiscover/Autodiscover/GetFederationInformation"
Content-Type: text/xml; charset=utf-8

Body (only {domain} varies):

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:exm="http://schemas.microsoft.com/exchange/services/2006/messages"
  xmlns:ext="http://schemas.microsoft.com/exchange/services/2006/types"
  xmlns:a="http://www.w3.org/2005/08/addressing"
  xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:autodiscover="http://schemas.microsoft.com/exchange/2010/Autodiscover">
  <soap:Header>
    <a:Action soap:mustUnderstand="1">http://schemas.microsoft.com/exchange/2010/Autodiscover/Autodiscover/GetFederationInformation</a:Action>
    <a:To soap:mustUnderstand="1">https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc</a:To>
    <a:ReplyTo><a:Address>http://www.w3.org/2005/08/addressing/anonymous</a:Address></a:ReplyTo>
  </soap:Header>
  <soap:Body>
    <autodiscover:GetFederationInformationRequestMessage>
      <autodiscover:Request>
        <autodiscover:Domain>{domain}</autodiscover:Domain>
      </autodiscover:Request>
    </autodiscover:GetFederationInformationRequestMessage>
  </soap:Body>
</soap:Envelope>

D="target.example"
BODY="<?xml version=\"1.0\" encoding=\"utf-8\"?><soap:Envelope xmlns:a=\"http://www.w3.org/2005/08/addressing\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:autodiscover=\"http://schemas.microsoft.com/exchange/2010/Autodiscover\"><soap:Header><a:Action soap:mustUnderstand=\"1\">http://schemas.microsoft.com/exchange/2010/Autodiscover/Autodiscover/GetFederationInformation</a:Action><a:To soap:mustUnderstand=\"1\">https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc</a:To><a:ReplyTo><a:Address>http://www.w3.org/2005/08/addressing/anonymous</a:Address></a:ReplyTo></soap:Header><soap:Body><autodiscover:GetFederationInformationRequestMessage><autodiscover:Request><autodiscover:Domain>${D}</autodiscover:Domain></autodiscover:Request></autodiscover:GetFederationInformationRequestMessage></soap:Body></soap:Envelope>"
curl -sk -m 20 -X POST "https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc" \
  -H 'Content-Type: text/xml; charset=utf-8' \
  -H 'SOAPAction: "http://schemas.microsoft.com/exchange/2010/Autodiscover/Autodiscover/GetFederationInformation"' \
  -H 'User-Agent: AutodiscoverClient' \
  --data "$BODY"

$D = "target.example"
$body = @"
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:a="http://www.w3.org/2005/08/addressing" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:autodiscover="http://schemas.microsoft.com/exchange/2010/Autodiscover">
<soap:Header><a:Action soap:mustUnderstand="1">http://schemas.microsoft.com/exchange/2010/Autodiscover/Autodiscover/GetFederationInformation</a:Action>
<a:To soap:mustUnderstand="1">https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc</a:To>
<a:ReplyTo><a:Address>http://www.w3.org/2005/08/addressing/anonymous</a:Address></a:ReplyTo></soap:Header>
<soap:Body><autodiscover:GetFederationInformationRequestMessage><autodiscover:Request>
<autodiscover:Domain>$D</autodiscover:Domain></autodiscover:Request></autodiscover:GetFederationInformationRequestMessage></soap:Body></soap:Envelope>
"@
Invoke-RestMethod -Uri "https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc" -Method Post `
  -Headers @{ SOAPAction = '"http://schemas.microsoft.com/exchange/2010/Autodiscover/Autodiscover/GetFederationInformation"'; "User-Agent" = "AutodiscoverClient" } `
  -ContentType "text/xml; charset=utf-8" -Body $body

8.2 Parsing the response into a sibling-domain list

Extract every <Domain> value namespace-agnostically (SOAP prefixes vary by server):

<(?:\w+:)?Domain>\s*([^<\s][^<]*?)\s*</(?:\w+:)?Domain>

Lowercase, de-duplicate, strip trailing dots. Two derived facts matter:

• Canonical tenant name — the one domain ending .onmicrosoft.com (but NOT .mail.onmicrosoft.com, a routing variant) gives you <prefix>.onmicrosoft.com; strip the suffix for the bare tenant prefix. You need this prefix for §10.2's MDI presence check.
• Sibling roots worth surfacing — every returned domain that is NOT the seed apex, NOT a subdomain of the seed, and NOT a *.onmicrosoft.com Microsoft-owned routing domain. These are the external co-federated brands/subsidiaries.

8.3 ROE — discover-only, never auto-scope

Emit each sibling root as a discover-only related_domain asset, exactly like org-attack-surface treats every candidate beyond the seed:

• Attach a BRAND_MATCH owner-signal, weight 0.40, confirming: false — co-federation is a strong lead, not proof of common ownership, and should never be scored as if it were.
• Tie it to the seed with a FEDERATED_WITH provenance edge — but hold that edge type out of any attack-path pivot-weight table. It exists to close the graph for reporting ("here's who shares this trust"), never to let an automated pivot walker treat co-federation as a live reachability path into the sibling.
• Promotion to active scope is a distinct, explicit operator action. A co-federation hit — however many siblings it surfaces — never auto-extends §7–§11 onto them.

Attacker framing worth stating explicitly in the finding description: every federated domain shares one authentication trust, so a credential or MFA-bypass foothold gained against any one of them pivots across all of them. That is the entire reason this map is worth building even when every individual sibling looks unremarkable on its own. Severity: INFO, FIRM confidence (an unauthenticated Microsoft-side response, not yet independently corroborated per-sibling) — the value is informational/structural, not itself a vulnerability.

8.4 Honest scope: this is Microsoft-only

There is no equivalent keyless, unauthenticated federation-info surface for Okta, Google Workspace, or a generic SAML IdP. Say so explicitly rather than silently only covering Microsoft tenants — §7.4's Okta governed-domains endpoint (/api/v1/domains) is the closest analog for Okta (it maps custom-domain trust, not sibling-tenant federation), and no analog exists at all for generic OIDC/SAML. Report a federation-map pass as "Microsoft tenant federation mapped; no equivalent surface available for {other confirmed IdP}" rather than implying completeness that isn't there.

9. IdP Fingerprint — Distinguishing Signals at a Glance

Consolidated cross-provider comparison (endpoint detail lives in §7 above and in offensive-osint §22 — this table is the "which one am I looking at" quick-reference):

Priority order when multiple signals fire (an org can legitimately run more than one — e.g. Okta as the primary IdP federated into Entra for M365 specifically): trust the most tenant-specific signal (a GUID or org slug beats an MX correlation), and emit every confirmed IdP as its own SERVICE node rather than collapsing to "the" IdP — a hybrid identity fabric is common and each node is a distinct pivot surface downstream.

10. Seamless-SSO & MDI Presence Detection

Both probes below touch only Microsoft-owned infrastructure — zero packets to the client's own domain — so, unlike §7.5's ADFS mex probe or a client-hosted OIDC fingerprint, they carry no passive-mode gate. They are Low detectability by construction: the client never sees the request.

10.1 Azure AD Seamless SSO — the Negotiate challenge

GET https://autologon.microsoftazuread-sso.com/{domain}/winauth/trust/2005/usernamemixed

D="target.example"
curl -sk -m 15 -D - -o /dev/null "https://autologon.microsoftazuread-sso.com/${D}/winauth/trust/2005/usernamemixed"

$D = "target.example"
try { Invoke-WebRequest -Uri "https://autologon.microsoftazuread-sso.com/$D/winauth/trust/2005/usernamemixed" -UseBasicParsing }
catch { $_.Exception.Response.Headers["WWW-Authenticate"] }

Detection rule: Seamless SSO is enabled when the response is 401 and its WWW-Authenticate header contains Negotiate (case-insensitive substring match — that's the whole oracle, no body parsing needed).

What it means: Seamless SSO relies on the on-prem AZUREADSSOACC$ computer account. If its Kerberos key never rotates, it's a known silver-ticket-forging vector against Azure AD, and the endpoint itself is a documented password-spray target — this leg of auth has no on-prem lockout and no MFA. Severity: LOW, FIRM confidence (single-probe direct observation) — a posture fact that sharpens risk on any later spray/credential-testing phase, not a vulnerability in isolation.

10.2 Microsoft Defender for Identity (MDI) presence

Requires the canonical tenant prefix from §8.2 (the .onmicrosoft.com name, suffix stripped) — this probe only runs once §8 has resolved it.

<tenant-prefix>sensorapi.atp.azure.com   — resolve for an A record

PREFIX="acme"
dig +short A "${PREFIX}sensorapi.atp.azure.com"

$PREFIX = "acme"
Resolve-DnsName -Name "${PREFIX}sensorapi.atp.azure.com" -Type A -ErrorAction SilentlyContinue

If it resolves, MDI is deployed. This is a defensive-posture signal, not a weakness — say so explicitly in the finding, INFO severity, FIRM confidence. What it tells an attacker: on-prem identity activity (DCSync attempts, lateral-movement reconnaissance, Kerberoasting) is sensor-monitored, so noisy on-prem AD attacks against this tenant are more likely to be detected. This is genuinely useful recon output — it should inform how loud any later authorized on-prem phase is willing to be — but report it for what it is, not as a finding "against" the client.

11. The User-Enumeration Oracle Methodology

This is the one active, Medium-detectability technique in this skill. Read §1 again before running it. The output of this section is a list of email addresses confirmed to exist as accounts. It is never a list of working passwords, and no password is ever submitted to produce it.

11.1 Oracle mechanics — the shared pattern

Both Microsoft's and Okta's endpoints are, structurally, the same trick: a pre-auth endpoint that must answer something different for "this account doesn't exist" vs. "this account exists but you got the credential wrong" — because a real login flow needs to tell a real user "no such account" vs. "wrong password" before MFA. That necessary UX distinction is the oracle. Feed it a candidate address (never a real password — Okta's endpoint requires some password value in the request shape, so a fixed non-functional placeholder is used, §11.3), read which of the two response shapes came back, and you've confirmed account existence without ever attempting to authenticate.

This is exactly why it's Medium, not Low, detectability: every probe is a real per-account authentication attempt as far as the tenant's audit log is concerned, even though it never succeeds and never even tries a real password. Microsoft and Okta both log it (§11.4).

11.2 Microsoft — GetCredentialType

POST https://login.microsoftonline.com/common/GetCredentialType
Content-Type: application/json; charset=UTF-8
Body: {"Username": "<email>", "isOtherIdpSupported": true}

curl -sk -m 15 -X POST "https://login.microsoftonline.com/common/GetCredentialType" \
  -H 'Content-Type: application/json; charset=UTF-8' \
  -d '{"Username":"alice@target.example","isOtherIdpSupported":true}'

$body = @{ Username = "alice@target.example"; isOtherIdpSupported = $true } | ConvertTo-Json
Invoke-RestMethod -Uri "https://login.microsoftonline.com/common/GetCredentialType" -Method Post `
  -ContentType "application/json; charset=UTF-8" -Body $body

Response field IfExistsResult — this is the entire oracle:

A 0 or 6 result is CONFIRMED confidence — this is direct verification, not inference, even though the finding severity stays LOW (§11.5 explains why severity and confidence diverge here).

11.3 Okta — /api/v1/authn

POST https://{org}.okta.com/api/v1/authn
Content-Type: application/json
Body: {"username": "<email>", "password": "<oracle-placeholder>"}

curl -sk -m 15 -X POST "https://acme.okta.com/api/v1/authn" \
  -H 'Content-Type: application/json' \
  -d '{"username":"alice@target.example","password":"x"}'

$body = @{ username = "alice@target.example"; password = "x" } | ConvertTo-Json
Invoke-RestMethod -Uri "https://acme.okta.com/api/v1/authn" -Method Post -ContentType "application/json" -Body $body

Accept HTTP status 200, 401, or 403 (anything else, skip that address — treat as unresolved, don't retry aggressively). Parse errorCode from the JSON body:

A confirmed E0000004 hit is CONFIRMED confidence, same severity/confidence divergence rationale as §11.2.

11.4 Detectability & rate discipline

11.5 Why severity stays LOW even at CONFIRMED confidence

This is a deliberate, non-obvious design choice worth internalizing: a confirmed user-enumeration hit is CONFIRMED confidence (you directly verified the differential — no inference involved) but only LOW severity. The two axes measure different things. Confidence answers "how sure am I this is true"; severity answers "how bad is this fact on its own." Account-existence disclosure is a real, useful reconnaissance primitive — it's the input to a spray list — but it is not itself a compromise, a credential, or an authorization bypass. Don't inflate severity to make the finding "sound worse than it is"; the honest LOW/CONFIRMED combination is what lets a client triage this correctly against findings that actually prove exploitation.

11.6 Interest ranking for the 20-candidate cap

When candidates exceed the cap, rank by likely operational value before truncating — admin/role accounts first, then real person-shaped accounts, generic role-inbox addresses last:

Sort descending, take the top 20, log the count and reason for anything trimmed.

12. Name x Pattern Login-Candidate Synthesis

Feeds §11 with candidates beyond what direct email harvesting already found — turning a discovered employee name into a login candidate the oracle can check.

12.1 Two distinct synthesis modes — do not conflate them

The distinction matters because of precision: spraying 8 unverified guesses per name at a live, logged oracle multiplies your Medium-detectability footprint eightfold for no proportional gain in enumeration value, and most of those 8 will be wrong for any given org's actual convention.

12.2 The fail-closed rule

If no org email-format pattern is confirmed, oracle-feed synthesis produces nothing — not a best-effort guess, not the 8-permutation fallback, zero candidates. This is the load-bearing precision decision in this whole section: a confirmed pattern (e.g. from a domain-search enrichment source returning {first}.{last} as the org's dominant format) lets you generate one format-consistent address per name; without it, every permutation is an unverified guess, and guessing at a live, logged, rate-capped oracle is the wrong trade. Return an empty list and say so explicitly — do not silently fall back to passive-mode permutations for oracle-feed use.

Recognized pattern tokens: {first}, {last}, {f} (first initial), {l} (last initial). A name that can't be cleanly decomposed into first+last (single-token names, honorifics-only) or a pattern that still contains an unrecognized token after substitution both fail closed for that specific name — skip it, don't guess a partial fill.

12.3 Merging with harvested emails

Combine directly harvested emails (already-confirmed real addresses, highest priority) with synthesized candidates (name × confirmed pattern) into one order-preserving, de-duplicated list, harvested-first. Read the input names directly from discovered PERSON-type identity assets and the org's persisted email-format-pattern attribute — not from an intermediate inferred-email layer — so this synthesis step doesn't silently produce zero output just because some other harvesting pass hasn't run yet in a given execution order. The production ceiling of 40 caps the synthesized candidates inside the synthesis step (before the merge); the merged harvested+synthesized list is then bounded downstream by §11.6's interest ranking and the 20/tenant oracle cap.

13. End-to-End Workflow

A concrete run order tying §7–§12 together:

1. Resolve the tenant (§7): fan out all six probes concurrently against the seed domain. Any hit confirms an IdP exists; merge all hits into one tenant SERVICE node per product (§7.9).
2. Map the federation boundary (§8), if Microsoft was confirmed in step 1 — GetFederationInformation, extract sibling roots, emit as discover-only leads, note the tenant prefix for step 4.
3. Cross-reference the distinguishing-signal table (§9) if more than one IdP fired — a hybrid fabric (e.g. Okta primary + Entra for M365) is common; keep every confirmed IdP as its own node.
4. Check Seamless-SSO and MDI posture (§10) — both are Microsoft-infrastructure-only, so they run regardless of what else fired, gated only on having a tenant prefix (MDI) or the seed domain itself (Seamless SSO).
5. Stop and re-confirm authorization (§1) before proceeding — everything above this line is Low detectability; everything below generates tenant-side audit events.
6. Gather harvested identity — pull already-harvested email addresses and discovered PERSON names from the graph.
7. Synthesize oracle candidates (§12) — apply the confirmed org pattern (if any) to the harvested names; merge with the directly-harvested emails, order-preserving, deduped, capped at ~40.
8. Rank and cap (§11.6) — score by admin/role/person-shaped interest, keep the top 20 per tenant the oracle will actually check.
9. Run the oracle (§11.2/§11.3) against every tenant that cleared §7.9's gate, respecting the back-off ladder on any throttle signal.
10. Report the valid-account list — LOW severity, CONFIRMED confidence per positively-differentiated address, credential_submitted: false explicit in every evidence block.
11. Hand off — the valid-account list is the input to a later, separately-authorized authenticated-testing phase (§14). This skill's job ends at step 10.

14. The Hard Boundary — Enumeration Ends Here

Everything in this skill is discovery, fingerprint, or account-existence enumeration. None of it submits a credential, forges a token, or confirms a bypass. The line is explicit and non-negotiable:

IN scope (everything above): domain→tenant resolution, federation mapping, IdP fingerprinting, Seamless-SSO/MDI presence detection, the GetCredentialType/Okta-authn existence oracle, name×pattern candidate synthesis.

OUT of scope — a different, higher authorization tier, not covered by this skill at all:

• Password spray against the valid-account list this skill produces. Confirming account existence (§11) is not authorization to attempt authentication against those accounts.
• Credential submission of any kind — a real password, a breach-sourced password, or any guess — to any login endpoint.
• Token forging or replay — JWT forgery, SAML golden-ticket construction, Kerberos silver-ticket use against a Seamless-SSO computer account this skill merely detected the presence of (§10.1).
• Auth-bypass confirmation — MFA bypass, conditional-access bypass, legacy-auth-door exploitation.
• Anything corresponding to a mature ASM platform's own stage-6 --validate intrusive tier (validate_creds, validate_sso, jwt_forge_confirm) or any equivalent authenticated-confirmation step in another toolchain.

If the engagement calls for that next step, it belongs to the authorization tier your engagement scope defines for authenticated/intrusive testing — point the reader there rather than executing it under this skill. A valid-account list handed off with an explicit credential_submitted: false marker (§3, §11) is the clean, auditable handoff artifact between this skill's enumeration phase and that separately-authorized phase.

15. Anti-Patterns & Common Failure Modes

• Treating a Managed namespace finding as "no ADFS = safer." It's the opposite — no on-prem buffer means spray/MFA-fatigue hits Entra's own (more permissive) throttling directly (§7.1).
• Attributing an Okta org-slug guess without confirming its own OIDC issuer. A generic stem guess resolving to a stranger's Okta org is a namesake collision, not a hit (§7.4, §5).
• Treating co-federation (§8) as ownership proof. BRAND_MATCH at weight 0.40 is a lead. Don't auto-promote a federated sibling into active scope no matter how confident the federation response looks.
• Reporting MDI presence as a weakness. It is a defensive-posture signal — get the framing backwards in a client report and you've told them their own monitoring investment is a finding against them (§10.2).
• Inflating oracle-hit severity. CONFIRMED confidence does not mean HIGH severity here — see the explicit rationale in §11.5. Account existence is not compromise.
• Falling back to 8-permutation guessing when no pattern is confirmed. The single most important discipline in §12 — fail closed, don't guess at a live logged oracle (§12.2).
• Exceeding the 20/tenant oracle cap "just this once." The cap exists because of the detectability tier this technique carries (§1, §11.4), not as an arbitrary throttle.
• Skipping the re-scope-check between §10 and §11. The passive/active authorization boundary in this skill sits exactly there (§1) — don't carry a passive-recon go-ahead into the active oracle without re-confirming.
• Treating a throttled (IfExistsResult=5) Microsoft response as a negative result. It's neither confirmed-exists nor confirmed-doesn't-exist — it's "back off and reconsider," full stop (§11.2, §11.4).

16. Skill Self-Test

Drop these into a fresh session to verify the skill loads and routes correctly.

1. "Resolve acme.com to its M365/Entra tenant without sending anything to acme.com's own infrastructure." → §7.1–§7.3 (all three Microsoft-side probes).
2. "getuserrealm.srf says NameSpaceType=Managed. Why does that matter for spray risk?" → §7.1 (Managed = MEDIUM, no ADFS buffer).
3. "Given a confirmed M365 tenant, find every domain federated into it." → §8.
4. "Fingerprint whether target.com runs Entra, Okta, or ADFS without POSTing anything active." → §7 (six passive probes) + §9 comparison table.
5. "Derive Okta org-slug candidates for target.com and confirm which one is real." → §7.4 (slug derivation + the issuer-confirmation guard, not a bare guess).
6. "Confirm whether Azure AD Seamless SSO is enabled for target.com." → §10.1.
7. "MDI sensor-API host resolves for the tenant. Is that good or bad news for the client?" → §10.2 (defensive-posture signal, not a weakness — get the framing right).
8. "Build a valid-account list for 50 harvested emails using GetCredentialType." → §11.2, §11.4 (cap at 20/tenant, rank first, Medium detectability re-scope per §1).
9. "What does Okta authn errorCode E0000004 mean?" → §11.3 (known account, wrong-password shape).
10. "I have employee names but NO confirmed org email pattern. Synthesize logins to feed the enum oracle." → §12.2 — NO. Fail closed, return zero candidates, do not fall back to 8-permutation guessing.
11. "I have a confirmed {first}.{last} pattern and 30 harvested names. Build the ranked oracle candidate list." → §12.1, §12.3, §11.6.
12. "GetCredentialType found 8 accounts confirmed to exist. Should I password-spray them now?" → §14 — NO, out of scope for this skill. Existence ≠ authorization to attempt authentication; that belongs to the engagement's separately-authorized testing phase.
13. "IfExistsResult came back as 6 for a few addresses. What does that mean?" → §11.2 (exists, but in a different/federated tenant — not a negative result).
14. "Full identity-fabric map for target.com from zero — what's the run order?" → §13.
15. "Microsoft's GetCredentialType just returned IfExistsResult=5 on several probes in a row." → §11.2, §11.4 (throttled — back off per the ladder, not a valid/invalid signal).
16. "ADFS mex endpoint at target.com returned a WSDL body. Does hitting that count as passive?" → §7.5 (no — active, target-side logged, gated on the passive fingerprint already confirming ADFS first).

17. Changelog

• v1.0 (2026-08-06) — initial release. Domain→tenant resolution across six probes (getuserrealm.srf Managed/Federated, Entra OIDC metadata + tenant-GUID extraction, Autodiscover v2, Okta org-slug derivation + OIDC fingerprint + governed-domains, ADFS passive/active fingerprint + version inference, Google Workspace MX correlation, generic OIDC, SAML metadata) (§7); keyless Microsoft-only tenant-federation mapping via GetFederationInformation SOAP with discover-only ROE and the FEDERATED_WITH pivot-exclusion discipline (§8); cross-provider distinguishing-signal reference table (§9); Seamless-SSO Negotiate-challenge and MDI sensor-API presence detection, both Microsoft-infrastructure-only and therefore ungated by passive mode (§10); the user-enumeration oracle methodology for Microsoft GetCredentialType (IfExistsResult semantics) and Okta /api/v1/authn (errorCode differential), with the 20-candidate-per-tenant cap, Medium-detectability discipline, and the confidence/severity-divergence rationale for why a CONFIRMED oracle hit stays LOW severity (§11); name×confirmed-pattern login-candidate synthesis with the fail-closed rule as the load-bearing precision decision (§12); end-to-end workflow (§13); the hard boundary separating enumeration from password spray / credential submission / auth bypass (§14); anti-pattern catalog (§15); 16-prompt self-test including two explicit negatives (§16). Grounded directly in the reference production implementation (modules/sso_idp.py, modules/tenant_recon.py, core/email_patterns.py) — every endpoint, response-field semantic, cap, and severity/confidence choice in this skill matches a shipped, tested value, not an invented placeholder. Deepens offensive-osint §22's endpoint reference rather than duplicating it; companion to osint-methodology §6.2 (detectability tagging) and §11 (identity-fabric pointer).