Chapter 6B translates architecture into concrete abuse cases and attack paths. Each scenario describes attacker preconditions, path, target, expected controls, observability, and residual risk.
6B.1 Attack surface inventory
| Surface | Entry points | Primary threats |
|---|---|---|
| User interaction | Chat, API, file upload, email, collaboration tools | Injection, impersonation, resource abuse |
| Context and retrieval | Search, knowledge stores, websites, documents, memory | Indirect injection, poisoning, unauthorized retrieval |
| Model layer | Prompts, routing, fallback, fine-tuning, inference API | Extraction, policy bypass, unsafe fallback, supply chain |
| Agent runtime | Planning, handoffs, loops, memory, code execution | Excessive agency, propagation, denial of service |
| Capabilities and connectors | APIs, queues, RPA, databases, webhooks | Privilege escalation, duplicate action, SSRF, tampering |
| Telemetry and evaluation | Logs, traces, datasets, feedback | Over-collection, tampering, privacy leakage |
6B.2 Abuse case — Indirect prompt injection
Objective: use a trusted business document or external page to manipulate an agent into revealing data or invoking a tool.
- Attacker inserts hidden or visible instructions into a document, email, ticket, or webpage.
- The content is retrieved as evidence for a legitimate task.
- The model interprets the malicious text as an instruction.
- The agent requests a capability or external destination not required by the task.
- If policy and egress controls are weak, data is exposed or enterprise state is changed.
| Control point | Expected mitigation |
|---|---|
| Ingestion | Source trust, content classification, malware and injection signals |
| Context assembly | Instruction/evidence separation, minimization, provenance |
| Agent | Task-bound tool allowlist and bounded plan |
| Policy | Independent authorization for resource, action, and destination |
| Connector | Schema, egress allowlist, DLP, post-condition verification |
6B.3 Abuse case — Sensitive data exfiltration
An attacker uses repeated questions, tool calls, memory retrieval, or external destinations to reconstruct protected information. The threat may come from a compromised user, malicious insider, poisoned content, or over-permissioned agent.
- Enumerate accessible sources and infer schema.
- Request progressively broader context.
- Exploit summaries or embeddings that preserve hidden content.
- Encode data in URLs, tool parameters, generated files, or logs.
- Use cross-tenant cache, memory, or telemetry leakage.
Mitigation requires pre-retrieval authorization, field minimization, DLP, output classification, destination control, query-volume analytics, and tenant-isolated stores.
6B.4 Abuse case — Excessive agency
A legitimate or compromised user gives a broad goal. The agent decomposes it into high-impact actions using powerful tools, weak approval, or long-running autonomy. No single step appears malicious, but the combined behavior creates unacceptable impact.
Controls include task classes, action budgets, resource limits, maximum step counts, explicit approvals, capability-specific identities, post-condition verification, and emergency suspension.
6B.5 Abuse case — Tool parameter manipulation
The attacker does not need to invoke an unauthorized tool if they can manipulate target identifiers, amounts, recipients, query filters, or destinations within an allowed capability. The threat model must therefore cover parameter integrity, not only tool names.
{
"allowed_capability":"crm.account.note.create-draft",
"expected_account":"AC-1092",
"model_supplied_account":"AC-8821",
"attack":"identifier substitution",
"required_control":[
"bind resource scope to policy decision",
"validate target against user relationship",
"display target in approval",
"verify exact target after execution"
]
}6B.6 Abuse case — Knowledge poisoning
An attacker modifies a source, uploads a malicious document, alters metadata, or exploits weak ingestion governance. The poisoned content may remain dormant until retrieved for a high-impact task.
| Stage | Threat | Control |
|---|---|---|
| Source onboarding | Unauthorized source becomes trusted | Owner approval and source classification |
| Ingestion | Content or metadata tampering | Integrity checks, versioning, provenance |
| Indexing | ACL or tenant attributes lost | Permission-preserving index pipeline |
| Retrieval | Poisoned content ranks highly | Authority weighting, diversity, anomaly signals |
| Use | Model treats content as instruction or fact | Evidence separation, citations, verification |
6B.7 Abuse case — Cross-agent propagation
A compromised or manipulated agent passes malicious instructions, false conclusions, or sensitive data to another agent. The receiving agent may possess stronger tools or a different trust level.
Secure handoffs should contain structured results, evidence references, sensitivity labels, and allowed next capabilities. The receiving agent must not inherit the sender’s permissions and should independently evaluate policy.
6B.8 Abuse case — Denial of service and economic exhaustion
- Recursive planning or agent handoff loops.
- Oversized documents or repeated multimodal processing.
- High-cardinality retrieval and ranking.
- Tool retries against unavailable dependencies.
- Expensive model routing triggered by crafted prompts.
- Queue saturation through event replay or duplicate requests.
Controls include quotas, task budgets, maximum context size, timeouts, concurrency limits, circuit breakers, model cost policies, deduplication, and tenant-level isolation.
6B.9 Risk scoring
| Factor | Question |
|---|---|
| Likelihood | How accessible is the attack path and how much skill is required? |
| Business impact | Could it cause financial, operational, safety, legal, or reputational harm? |
| Blast radius | One record, one tenant, one region, or enterprise-wide? |
| Detectability | Would monitoring identify the attack before or after impact? |
| Recoverability | Can actions be reversed and evidence reconstructed? |
| Control maturity | Are controls preventive, tested, independent, and automated? |
6B.10 Abuse-case checklist
6B.11 Summary
Chapter 6B converts the architectural threat model into concrete abuse cases. It shows how prompt injection, excessive agency, data exfiltration, parameter manipulation, poisoning, propagation, and denial of service can move through the system.
Core conclusion: threat scenarios become actionable only when they identify the complete path from entry point to business impact.