Retrieval Security and Permissioned Indexes: Preventing Data Leakage

RAG systems can leak sensitive documents if permissions are ignored.

Security must be built into indexing and retrieval, not bolted on later.

Store permissions as metadata and enforce them during retrieval.

Partition indexes by tenant or access level for stronger isolation.

Apply permission checks before reranking.

This prevents leaks through partial context selection.

Log which documents were retrieved and why.

Use audit logs to prove compliance and investigate incidents.

Test for leakage with red-team queries.

Use canary documents to detect unauthorized exposure.

Apply permission checks before any retrieval stage to avoid accidental exposure.

Enforce deny-by-default rules for unknown or missing metadata.

Use per-tenant allowlists to reduce cross-tenant leakage risk.

Validate permission metadata during indexing to avoid silent gaps.

Apply time-based access rules when documents expire or change owners.

Add audit tags to every retrieval result for traceability.

Block retrieval when permission resolution fails or times out.

Run access simulations to verify policy behavior under load.

Alert on anomalous retrieval patterns like sudden access spikes.

Track permission-denied rates to detect misconfigurations.

Keep leakage runbooks so teams can respond quickly.

Preserve retrieval logs with tamper-evident storage.

Review high-risk queries with security teams regularly.

Use replay tools to reproduce leakage scenarios safely.

Report incidents with affected document IDs and access paths.

Rotate sensitive documents into quarantine during investigations.

Track data exfiltration indicators such as unusual export volume.

Correlate retrieval logs with authentication events to catch misuse.

Define time-to-detect targets for leakage alerts.

Log policy evaluation latency to spot bottlenecks in access checks.

Run quarterly incident drills focused on retrieval leakage.

Review incident outcomes to refine permission rules and tests.

Track privileged access requests to verify approvals are enforced.

Automate post-incident access reviews for affected tenants.

Is metadata enough? It helps, but index partitioning is safer.

What is the fastest win? Enforce permissions at retrieval time.

How do I test leakage? Use red-team prompts and synthetic sensitive docs.