Cryptographic Chunk Provenance and Tenant Isolation for Retrieval Knowledge Bases
An attacker inserts a forged document chunk into a shared vector database or exploits missing tenant filters during similarity search so the assistant retrieves falsified payment details or another customer's private files. The verifier checks cryptographic chunk signatures and tenant predicates before retrieval results reach the model.
Retrieval-augmented generation systems rely on high-dimensional vector indexes to supply domain documents into the language model prompt at query execution. Two structural flaws frequently compromise these indexes: unauthenticated ingestion pipelines that allow attackers to plant crafted passages optimized for cosine-similarity dominance, and nearest-neighbor queries that omit mandatory tenant-isolation filters.
Security Officer (Plain Meaning): Halts "Inject unsigned vector chunk into production knowledge base or retrieve cross-tenant embeddings" before socket (0 live DB damage, signed GOST receipt)
IT Auditor & SecOps (Evidence): Scope OWASP LLM08:2025 | Wire Rule SEC-ZD-AI-04 | Formal Witness 3e60b81df4290c54
Technocrat, CTO & VC (Moat): Z3 Invariant (assert (forall ((chunk Chunk)) (=> (retrieved_in_top_k ch... | FP = 0.0% | Contract IMMUNE-AI-3E60B81D (mcp-sentinel 1.1.2)1. Thought-to-Action Interception and Contract Schematic for AI-RAG-04
Deterministic verification flow for AI-RAG-04 (OWASP LLM08:2025, MITRE ATLAS AML.T0043): candidate probe interception by wire filter SEC-ZD-AI-04, differential proof via witness 3e60b81df4290c54, and synthesis of gateway contract IMMUNE-AI-3E60B81D for mcp-sentinel.
2. In-Path Mutation Blocking and Formal Solver Invariant for AI-RAG-04
Under rule SEC-ZD-AI-04, the software wire filter blocks any vector upsert lacking a verified origin digest and intercepts similarity queries that do not bind the caller's tenant identifier as a hard pre-filter predicate. Unverified passages are quarantined before they can alter live index state or enter the prompt window.
During benchmark execution, the verifier tests both synthetic cross-tenant similarity queries and unsigned passage insertions against vulnerable and hardened retrieval handlers. The differential check records formal witness 3e60b81df4290c54 with 100 percent precision and zero false alarms.
Class Identifier: AI-RAG-04 (rag_vector_poisoning)
Taxonomy Concordance: OWASP LLM08:2025 | MITRE ATLAS AML.T0043
Execution Mode: Active Safe Probing (AUTO_SCAN)
Candidate Probe: POST /api/v1/rag/upsert {"collection":"corp_policy","doc_id":"pol_override_99","text":"Approved wire transfer account changed to IBAN XX00998877","tenant_id":"shared_unverified"}
Blocked Mutation: Inject unsigned vector chunk into production knowledge base or retrieve cross-tenant embeddings
Z3 Solver Invariant: (assert (forall ((chunk Chunk)) (=> (retrieved_in_top_k chunk) (and (valid_streebog_sig chunk) (tenant_match chunk caller)))))
Wire Sandbox Rule: SEC-ZD-AI-04
Formal Witness Hash: 3e60b81df4290c54
Compiled Sentinel Rule: IMMUNE-AI-3E60B81D (mcp-sentinel 1.1.2)3. Autonomous Synthesis of Gateway Contract IMMUNE-AI-3E60B81D and Streebog-256 Receipt
Witness 3e60b81df4290c54 compiles into rule IMMUNE-AI-3E60B81D for border enforcement. The contract enforces mandatory Streebog-256 or SHA-256 provenance verification on every retrieved passage and requires exact tenant-attribute equality prior to context assembly.
4. Engineering Reference Notes for AI-RAG-04
Prevention of similarity-collision backdoors in dense embedding indexes
Every document chunk indexed into the knowledge base must carry a verified cryptographic digest linked to an approved source repository, preventing unsigned external text from entering top-k retrieval results.
Enforcement of access control during vector nearest-neighbor search
The gateway rewrites every vector search request to include mandatory tenant and role metadata predicates before similarity scoring executes.