Security: session endpoints bypass owner authorization check #132

Summary

GET /api/sessions and POST /api/session/attach are incorrectly exempted from the before_request authorization check in authorize_request(). This allows any authenticated Databricks user (not just the app owner) to:

1. List all active terminal sessions — discover session IDs, labels, process info
2. Read buffered terminal output — attach to any session and retrieve its output buffer, which may contain secrets, credentials, or sensitive code

Root Cause

The authorize_request() before_request hook at app.py:782 exempts these paths:

if request.path in ("/health", "/api/setup-status", "/api/pat-status",
    "/api/configure-pat", "/api/app-state",
    "/api/sessions",          # <-- BUG: skips owner check
    "/api/session/attach"     # <-- BUG: skips owner check
) or request.path.startswith("/socket.io"):
    return None

These exemptions were added incrementally during session management feature work to support the session-reconnect UX, but they bypass the security boundary.

Note: POST /api/session (create) and POST /api/session/close are NOT exempted and correctly enforce authorization.

Impact

• Severity: High — unauthorized data access (terminal output may contain secrets)
• Affected deployments: All Databricks Apps deployments since session management was added
• Not affected: Local development (auth is open by default)

Fix

Remove /api/sessions and /api/session/attach from the exemption list. The session-reconnect flow works correctly because the frontend already sends the SSO identity headers with every request — the auth check just wasn't being applied.

Secondary Finding: Missing Case-Insensitive Test Coverage

The existing 16 auth tests all use same-case email data. No test verifies that mixed-case SSO headers (e.g., Owner@Databricks.COM) match the lowercase-normalized owner — the exact scenario commit 6bd8ecf was supposed to fix.

Test Coverage Added

• 10 new endpoint-level tests: deny/allow for all 5 session endpoints (/api/sessions, /api/session/attach, /api/session, /api/session/close, /api/resize)
• 7 case-insensitive tests: mixed-case, all-caps, alternating-case for HTTP auth, WS auth, and get_request_user() normalization