Any access path into a system that is not obvious in the primary network design, such as vendor tooling, shared services, or remote monitoring. In OT, indirect connectivity is often the reason an environment that appears isolated still has real exposure to external or adjacent threats.
Expanded Definition
Indirect connectivity describes access paths that bypass the obvious, intended route into a system. In practice, that can include vendor remote support channels, shared authentication services, jump hosts, management planes, backup links, telemetry collectors, or remote monitoring tooling. The key security issue is not whether the connection is “networked” in the broad sense, but whether it creates a reachability path that is easy to overlook during design, inventory, or risk review.
For NHI Management Group, the operational concern is that indirect paths often concentrate trust in places defenders do not inspect as closely as production traffic. In OT and critical infrastructure environments, an architecture may appear segmented while still depending on hidden pathways that enable administrative access or data movement. That makes indirect connectivity a governance issue as much as a topology issue, because it affects asset visibility, trust boundaries, and the credibility of isolation claims. NIST Cybersecurity Framework 2.0 treats asset understanding and access governance as part of a defensible security posture, which is why indirect routes belong in the same review cycle as privileged access and external exposure.
The most common misapplication is treating indirect connectivity as harmless “support access,” which occurs when organisations document the primary network diagram but leave vendor, cloud, or monitoring paths out of scope.
Examples and Use Cases
Implementing controls for indirect connectivity rigorously often introduces operational friction, requiring organisations to weigh easier maintenance against tighter oversight, logging, and approval processes.
- Remote vendor support reaches an OT controller through a jump server and session broker, creating a path that is not visible on the core production diagram.
- A cloud-based monitoring platform polls on-premise assets through a management connector, making external reachability depend on a service that sits outside the main trust boundary.
- A shared identity provider authenticates admins across IT and OT, so a compromise in the corporate environment can affect systems that were assumed to be isolated.
- Backup or replication traffic uses a separate management network, and that network becomes the practical route into sensitive systems during an incident.
- Third-party tooling uses API keys or service accounts to move configuration data, which creates an indirect access path even when no human logs in interactively.
These patterns are easier to miss when teams rely on high-level segmentation claims rather than a path-by-path review. Guidance from NIST Cybersecurity Framework 2.0 is useful here because it pushes organisations toward knowing what is connected, who can reach it, and through which mechanisms. In operational reviews, the question is not only whether the path exists, but whether it is governed, monitored, and justified.
Why It Matters for Security Teams
Indirect connectivity matters because it often defeats the assumptions that make segmentation, isolation, and least privilege seem stronger than they are. Security teams can design robust perimeter controls and still leave a hidden route open through support tooling, shared credentials, or a delegated management plane. That is especially important in environments where NIST Cybersecurity Framework 2.0 principles are applied to critical assets, since exposure can arise from relationships between systems rather than from direct inbound traffic.
For identity and access governance, indirect connectivity is also where non-human identities become relevant. Service accounts, API tokens, orchestration tools, and vendor-managed identities often carry the permissions that make these paths usable. If those identities are over-privileged or poorly rotated, an indirect route becomes a durable foothold instead of a controlled exception. The same is true in agentic AI deployments, where tool-enabled agents may inherit network access that was never intended for autonomous execution.
Organisations typically encounter the consequence only after an incident review or third-party access failure, at which point indirect connectivity becomes operationally unavoidable to map, constrain, and monitor.
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 address the attack surface, NIST CSF 2.0, NIST SP 800-53 Rev 5 and NIST Zero Trust (SP 800-207) set the technical controls, and ISO/IEC 27001:2022 define the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | ID.AM-1 | Indirect connectivity depends on knowing assets and communication paths across the environment. |
| NIST SP 800-53 Rev 5 | AC-17 | Remote access controls directly govern many indirect connectivity channels. |
| ISO/IEC 27001:2022 | A.8.20 | Network security controls support identification and restriction of non-obvious access paths. |
| OWASP Non-Human Identity Top 10 | Indirect connectivity often relies on non-human identities, secrets, and delegated service access. | |
| NIST Zero Trust (SP 800-207) | Zero trust assumes paths are untrusted until explicitly verified, fitting hidden connectivity risks. |
Inventory hidden routes and service dependencies before they become ungoverned exposure.
Related resources from NHI Mgmt Group
- How should security teams reduce indirect prompt injection risk in AI systems?
- When does indirect prompt injection become a business risk rather than a technical curiosity?
- Why do indirect prompt injections matter for IAM and NHI governance?
- Why is indirect prompt injection harder to defend than XSS?
