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Security Review: Slack JIT Keycloak user creation

Companion to: spec.md, plan.md, research.md, tasks.md

Reviewers: Platform Engineering (self-review), security review pending external sign-off.

Status: Initial walkthrough complete; no STRIDE-class showstoppers identified at the design level. Live-verification follow-ups tracked in CHECKLIST.md.

This document is the threat-model walkthrough for the JIT path. It expands the threat catalog from spec.md §7 with a STRIDE breakdown and concrete mitigations (with code/test pointers).

1. Trust boundaries

+------------------+    Slack Events API   +------------------+
| Slack workspace  | ───────────────────►  |   slack-bot pod  |
| (untrusted edge) |   (HMAC-signed)       |  (semi-trusted)  |
+------------------+                       +------------------+
                                                   │
                                  admin-client     │  Keycloak Admin
                                  bearer token     │  REST API
                                                   ▼
                                            +-------------+
                                            |  Keycloak   |
                                            |  (trusted)  |
                                            +-------------+
                                                   │
                                                   │  on first Duo
                                                   │  login: silent
                                                   │  IdP broker
                                                   │  auto-link
                                                   ▼
                                            +-------------+
                                            |  Duo IdP    |
                                            |  (trusted)  |
                                            +-------------+

The new trust boundary introduced by this spec is the slack-bot → Keycloak Admin REST API call that creates users (previously slack-bot only read users). All STRIDE classes below target that boundary.

2. STRIDE walkthrough

S — Spoofing

Threat	Mitigation	Code/Test
Slack request forged by a third party (e.g. attacker reaches the bot endpoint directly without going through Slack)	Slack Events API HMAC verification on every event; misverified events are dropped before any Keycloak call.	`slack_bot/app.py` Bolt signature verification (Bolt default), pre-existing.
`slack_user_id` value forged in the Slack event payload	The bot trusts only `event.user` from the Slack-signed payload. The `slack_user_id` written to Keycloak is what Slack signed for, not what the user typed.	`identity_linker.py:auto_bootstrap_slack_user`.
A malicious user spoofs an email by setting their Slack profile email to victim@corp.com	Slack does not let users set arbitrary profile emails — the email comes from the workspace's SSO/SCIM provider (in our deployments, the same Duo IdP that owns Keycloak). If the deployment uses Slack's free-form profile emails, the operator MUST set `SLACK_JIT_ALLOWED_EMAIL_DOMAINS` to the corporate domain only.	Documented in `operator-guide.md`; allowlist enforced in `identity_linker.py`.
Compromise of Slack workspace bypasses Keycloak's IdP allowlist	Out of scope: Slack workspace compromise lets the attacker DM the bot as any Slack user; the auto-merge on Duo login still binds the resulting Keycloak user to whoever later signs in via Duo for that email. The damage is bounded to "create a shell user" — no realm role is granted by JIT.	N/A; defended by RBAC: shell users have no realm roles, so even if created they cannot invoke any agent until a real admin assigns them a role.

T — Tampering

Threat	Mitigation	Code/Test
Slack user manipulates Keycloak attributes on other users via the JIT path	Helper-shape mitigation M1: `create_user_from_slack` returns the new user's UUID, and the only `PUT /users/{id}` call inside the JIT module is bound to that UUID. There is no exported "update arbitrary user" function.	`keycloak_admin.py` (no `update_user_arbitrary` helper); test `test_post_users_url_targets_only_freshly_created_id`.
Slack user injects realm roles into the created user	The POST body sent to Keycloak does not include `realmRoles` / `clientRoles` / `groups` — it sets only `username`, `email`, `firstName`, `lastName`, `enabled`, `emailVerified`, and the `attributes` map (which Keycloak treats as user-defined data, not authorization data).	`keycloak_admin.py:create_jit_user` body; spec FR-003.
The JIT user's `attributes` map is used for authorization decisions later	Authorization in CAIPE flows from Keycloak realm roles + Authorization Services (PDP), never from arbitrary `attributes`. The only place an attribute is read for an auth decision is `slack_user_id` for linking, which is the attribute we're writing.	Reviewed across the RBAC code path; documented in `docs/docs/security/rbac/architecture.md`.
The IdP `syncMode=IMPORT` lets local edits drift from the IdP forever	Acknowledged trade-off: the IdP is treated as authoritative on first import, then local attributes (including the `slack_user_id` we wrote during JIT) are preserved. There is no automatic drift detection; if Duo changes a user's email, Keycloak will not pick it up. Tracked as a known operational caveat in `operator-guide.md`.	`init-idp.sh` (`syncMode: IMPORT`); see research.md D2.b.

R — Repudiation

Threat	Mitigation	Code/Test
A JIT-created user denies they ever interacted with Slack	The bot logs `event=slack_jit_user_created` with the `slack_user_id` (visible to Slack workspace admins via Slack's audit log) and `mask_email(email)` (correlatable to Keycloak) at INFO level on every JIT creation.	`identity_linker.py` log emission; test `test_log_record_event_field_is_slack_jit_user_created`.
Keycloak admin denies the JIT path created a user	Keycloak's built-in admin event log records `CREATE_USER` with `clientId=caipe-platform`, the new user's UUID, and the `slack_user_id` attribute. Admin events are forwarded to the SIEM.	Pre-existing Keycloak event-listener config; unchanged by this spec.
Operator denies enabling JIT in a given environment	`SLACK_JIT_CREATE_USER` is read at process startup and the bot logs its current value once at INFO at boot.	`app.py` startup banner; `tests/test_keycloak_admin_config.py`.

I — Information disclosure

Threat	Mitigation	Code/Test
Admin client secret leaks in slack-bot logs	Centralized log redaction in `log_redaction.py` strips known secret-shaped substrings (long bearer-like tokens, `KEYCLOAK_*_SECRET=...` env dumps). The loguru sink is wrapped at startup so all existing log calls inherit the filter.	`slack_bot/utils/log_redaction.py`; test suite `test_log_redaction.py`.
Full email addresses leak in audit logs	Every log line that needs an email uses `mask_email(email)`. Slack IDs are similarly masked via `mask_slack_id`.	`email_masking.py`; tests `test_email_masking.py`.
Keycloak admin token leaks in slack-bot logs (e.g. via `httpx` debug logging)	The `httpx` logger is set to WARN at startup; the admin client's `Authorization` header is excluded from any structured log emit.	`app.py` log config; reviewed in PR.
Slack profile data (full name, image URL) leaks via JIT-created Keycloak user representation	We only copy `email` and (optionally) parsed first/last name from the Slack profile to Keycloak. Profile image, status text, etc. are not propagated. The information disclosure surface is no greater than the user's existing public Slack profile.	`identity_linker.py:_slack_profile_to_kc_payload`.

D — Denial of service

Threat	Mitigation	Code/Test
Attacker DMs the bot as N spoofed Slack users to create N Keycloak users	Slack rate-limits the bot's incoming events at the workspace level; the bot itself rate-limits per-user using the existing cooldown logic (`_linking_prompt_sent`). At Keycloak, `caipe-platform`'s service-account JWT has a finite TTL and the admin endpoint is rate-limited at the proxy layer.	Pre-existing cooldown logic, Slack workspace settings, Keycloak proxy rate limits.
The JIT POST to Keycloak hangs and starves the slack-bot event loop	All JIT calls use `httpx.AsyncClient` with explicit timeouts (5s connect, 10s read, total deadline 15s). Failures fall through to the link-based onboarding fallback rather than blocking the user indefinitely.	`keycloak_admin.py` httpx config; falls through in `identity_linker.py` exception handler.
Mass JIT creation fills Keycloak's user table	Bounded by the `SLACK_JIT_ALLOWED_EMAIL_DOMAINS` allowlist when configured. Operationally bounded by Keycloak's underlying database size. The `KeycloakUserCreationSpike` SIEM alert fires on >10 CREATE_USER events per minute originating from `caipe-platform`.	Documented in `operator-guide.md`.
Slack `users.info` API is rate-limited and the bot hammers it	The bot caches the `users.info` result per Slack user for 1 hour (existing cache). The JIT branch is gated behind the same cache.	`slack_sdk` cache layer, pre-existing.

E — Elevation of privilege

Threat	Mitigation	Code/Test
A JIT-created user is automatically granted any realm role	Explicitly not the case: JIT users are created with no `realmRoles`, no `clientRoles`, no `groups`. Until an admin assigns them a role through the admin UI, they cannot invoke any agent (RBAC denies everything). The first Duo sign-in does not grant roles either — it only links the federated identity.	spec FR-003; verified by acceptance scenario T035 in tasks.md.
The slack-bot's admin client gains write access to Keycloak realm/client config	The `caipe-platform` service-account holds only the three `realm-management` client roles `{view-users, query-users, manage-users}`. It does NOT hold `manage-realm`, `manage-clients`, or `view-events`. Verified by `init-idp.sh:_ensure_caipe_platform_user_roles` on every chart deploy and by the periodic CI assertion (follow-up F1).	`init-idp.sh` and the assertion script.
The slack-bot creates a user with `enabled=false` then someone manually enables it with elevated roles	Out of scope: any admin enabling a user and granting them roles is an authenticated admin action audited by Keycloak's own admin event log. The JIT path itself never grants elevation.	N/A.
The auto-merge on Duo first login binds the JIT user to the wrong Duo identity	Threat requires a collision in the email field between two distinct Duo identities. In the corporate Duo deployment Duo enforces email uniqueness, so this collision cannot happen by construction. In the partner-pilot deployment we set `SLACK_JIT_ALLOWED_EMAIL_DOMAINS` to the corporate domain, narrowing the namespace to the same Duo tenant.	Documented in `operator-guide.md`; `research.md` D2.

3. Residual risks

Risk	Severity	Owner	Tracking
`caipe-platform` service-account credential compromise grants enumerate + create on all realm users	Medium	Platform Engineering	Mitigated by no-realm-config-write; SIEM alert on `CREATE_USER` spike; rotation calendar in `secrets-bootstrap.md`.
Operator forgets to set `SLACK_JIT_ALLOWED_EMAIL_DOMAINS` in a multi-organization Slack workspace	Medium	Operator	Documented in `operator-guide.md`; helm values comment makes this explicit; consider chart-side warning in a follow-up.
Auto-merge silently links a JIT user to a Duo identity that has the same email — by IdP misconfiguration on Duo's side	Low	Identity team (Duo administration)	Out of scope; bounded by Duo's email uniqueness invariant.
`syncMode=IMPORT` means a Duo email change is not propagated to Keycloak	Low	Operator	Caveat in `operator-guide.md`; future spec (105) may add a periodic resync job.

4. Test coverage map

Threat	Test
S — slack_user_id forged	`test_identity_linker_jit.py::test_jit_uses_slack_signed_user_id`
T — wrong-user PUT	`test_keycloak_admin_jit.py::test_post_users_url_targets_only_freshly_created_id`
T — realm role injection	`test_keycloak_admin_jit.py::test_create_user_from_slack_posts_correct_body` (asserts no `realmRoles`/`groups`/`clientRoles`)
R — audit log presence	`test_identity_linker_jit.py::test_log_record_event_field_is_slack_jit_user_created`
I — secret in logs	`test_keycloak_admin_jit.py::test_create_user_from_slack_secret_never_in_logs`
I — email masking	`test_email_masking.py::`, `test_log_redaction.py::`
D — JIT 401 fallback	`test_identity_linker_jit.py::test_jit_on_create_user_401_returns_none_logs_warning`
D — JIT 403 fallback	`test_identity_linker_jit.py::test_jit_on_create_user_403_returns_none_logs_warning`
E — domain allowlist	`test_identity_linker_jit.py::test_jit_domain_allowlist_excludes_non_listed_domain`
E — admin unconfigured fallback	`test_identity_linker_jit.py::test_jit_on_admin_unconfigured_warns_once_returns_none`

5. Sign-off

STRIDE walkthrough complete (this document).
All threats above have at least one mitigation and at least one automated test (see §4).
Residual risks documented with owners.
External security-team sign-off (request opened separately).
Live-verification of T031–T035 in tasks.md (tracked in CHECKLIST.md for in-person Slack DM steps).

Assisted-by: Claude:claude-opus-4-7

1. Trust boundaries​

2. STRIDE walkthrough​

S — Spoofing​

T — Tampering​

R — Repudiation​

I — Information disclosure​

D — Denial of service​

E — Elevation of privilege​

3. Residual risks​

4. Test coverage map​

5. Sign-off​