testland/cross-tenant-data-leak-tests
Workflow-driven skill that plans and implements the cross-tenant leak-test suite - from surface inventory to the runtime CI gate a multi-tenant codebase must pass on every PR. The planning section inventories tenant-bearing surfaces (tables, APIs, object storage, search, queues, caches), classifies each by isolation model (silo / pool / bridge, per references/isolation-models.md), and derives the OWASP WSTG-ATHZ-02 coverage matrix. The battery defines the canonical test patterns (read-other-tenant-by-id, list-leak, spoofed-tenant-id-in-body, JWT-replay, FK-cross-tenant, unique-collision side channel, object-storage IDOR, search-index-direct-query, async-job-context-reload, cache-key-collision), the 404-vs-403 disclosure trade-off, the Postgres-RLS-direct patterns, and the CI integration (non-superuser non-BYPASSRLS role, fail the build on any leak). Use when designing or implementing a tenant-isolation test suite, adding the CI gate to an existing project, or investigating a leak finding.
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attack-patterns.mdreferences/
Tenant-leak attack patterns
OWASP WSTG-ATHZ-02 scenarios
Three primary authorization-bypass scenarios apply to every pool/bridge surface:
| Pattern | What | Surface |
|---|---|---|
| Horizontal escalation | Tenant A accesses tenant B's data at identical privilege | All pool/bridge surfaces |
| Vertical escalation | Non-admin in tenant A accesses admin-only resources | All admin-scoped surfaces |
| IDOR / BOLA | Direct reference attack - change an ID in URL/payload | All ID-bearing endpoints |
Tenant-isolation-specific patterns
| Pattern | Test |
|---|---|
| tenant_id from request payload | Send tenant A's session with tenant_id=B in body - must reject |
| Missing tenant_id filter in new endpoint | Enumerate routes added in last N commits; verify each filters by tenant |
| Cross-tenant via foreign key | Create FK from tenant-A row to tenant-B row - must fail |
| Cross-tenant via unique constraint | Insert tenant-A row with a key that exists in tenant B - observe error timing as a side channel |
| JWT replay across tenants | Tenant A's JWT used to call tenant B's endpoint - must reject on signature/iss/aud check |
| Object storage path traversal | Tenant A presigned URL -> modify prefix to tenant B's - must 403 |
| Search query without tenant filter | Direct search index query - must include the tenant routing key |
| Async job tenant context | Job enqueued by tenant A -> executor must reload tenant context, not trust the message |
| Cache key collision | Tenant A and tenant B have the same logical key - cache must namespace |
| Log scrubbing | Tenant A errors must not leak tenant B identifiers |
Source: OWASP WSTG-ATHZ-02 Testing for Bypassing Authorization Schema owasp.org/www-project-web-security-testing-guide/v42/4-Web_Application_Security_Testing/05-Authorization_Testing/02-Testing_for_Bypassing_Authorization_Schema.