An inventory of the tools, APIs, data classes, and access paths a system actually uses while running. For AI agents, it matters because declared intent is not enough to govern privilege when behavior can change during execution.
What a runtime-derived bill of materials captures
A runtime-derived bill of materials is not a design-time inventory, it reflects the tools, APIs, data classes, and access paths a system actually touches while executing. That distinction matters because real behaviour can diverge from declared architecture, especially in adaptive software and agentic systems.
The value of the term is that it shifts attention from what developers intended to what the system exercised in production. That makes it a more realistic basis for governance, exposure analysis, and control validation when dynamic calls, deferred loading, or runtime decisions change the effective attack surface.
Why runtime evidence matters more than declared intent
A static inventory can say a component is allowed to use certain services, but a runtime view shows which dependencies were actually invoked, which data classes were exposed, and which execution paths became reachable. For security teams, that helps separate theoretical capability from observed behaviour.
This is especially important in systems that assemble behaviour on the fly, because privilege and access paths may expand only during execution. Runtime evidence therefore helps surface hidden dependencies, excessive reach, and unexpected trust relationships that would be missed by a purely declared bill of materials.
What belongs in the inventory
The most useful runtime-derived inventories focus on the concrete things the system interacted with: libraries and tools that were loaded, APIs that were called, data categories that were processed, and the access paths used to reach them. For AI-enabled systems, that can include model calls, tool invocations, retrieval paths, and any services that became reachable through orchestration.
That scope makes the inventory closer to an operational map than a catalog of source artifacts. It captures the security-relevant footprint that exists during execution, including dependencies introduced by configuration, context, or agent behaviour, not just the ones documented in advance.
Seen as a governance artifact, a runtime-derived bill of materials helps answer a practical question: what was this system really able to touch when it ran? AI Supply Chain Security and AI-BOM Guide is relevant here because it frames inventories around the actual supply-chain and credential-containment exposure that AI systems create.
How it changes security review
A runtime-derived inventory changes review from assumption-based to evidence-based. Instead of asking only whether a dependency was approved, teams can check whether it was used, whether it introduced access to sensitive data, and whether the resulting path matched the system’s intended trust model.
That is useful for detecting drift, validating least privilege, and identifying overbroad access paths that emerged at runtime. It also supports incident analysis, because a runtime record can show which tools, APIs, and data classes were in play when a compromise or unexpected action occurred.
Risk and Threat Considerations
Runtime-derived inventories reduce blind spots, but they also reveal how much risk can hide in live execution. When a system can assemble tools, credentials, or access paths dynamically, attackers can target the runtime path rather than the documented design.
Failure mechanism: A system may appear constrained on paper while runtime behaviour opens additional APIs, data flows, or delegated access that were never reviewed, creating a gap between approved architecture and actual exposure.
Impact: That gap can enable overprivilege, unauthorized data access, supply-chain misuse, or unexpected downstream actions, and it can make incident triage slower because defenders must reconstruct what the system truly touched.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 addresses the attack and risk surface, while NIST SP 800-53 Rev 5 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | CA-7 — Continuous Monitoring | Runtime-derived inventories support continuous observation of actual system behavior. |
| CM-8 — System Component Inventory | This term is an execution-time extension of component inventory and asset visibility. | |
| SA-10 — Developer Configuration Management | Observed runtime dependencies help validate and govern what software actually deploys and invokes. | |
| Recommendation — Use CA-7 to verify live dependencies and access paths against intended security posture. Use CM-8 to maintain an inventory that includes components and dependencies observed at runtime. Use SA-10 to control and review runtime-relevant dependencies before they expand exposure. | ||
| OWASP Non-Human Identity Top 10 | NHI-03 — Vulnerable Third-Party NHI | Runtime inventories surface third-party tools and access paths that can widen identity and dependency risk. |
| NHI-05 — Overprivileged NHI | The term directly exposes when live execution grants more access than intended. | |
| Recommendation — Map runtime-discovered third-party access to NHI-03 and remove unreviewed dependency exposure. Use NHI-05 to reduce runtime access paths that exceed the system's intended privilege. | ||
Practitioner Guidance
Why practitioners should care: Treat the runtime-derived bill of materials as an operational control input, not a documentation exercise. It is most valuable when teams use it to compare declared behaviour with observed behaviour and then decide whether access, tooling, or data exposure needs to be reduced.
Common misunderstanding: A system that is approved at design time is not automatically safe at runtime. When execution is dynamic, the live footprint can be broader than the original architecture review, so the inventory should be refreshed and interpreted in context.