Automated traffic generated by systems, services, or agents rather than human users. For fraud and identity teams, the issue is not whether the traffic is machine-originated, but whether it is trusted, traceable, and aligned to the scope that was actually approved.
Expanded Definition
Machine-to-machine traffic is the operational layer where services, workloads, scripts, and agents exchange data without a person actively driving each request. In NHI security, the key question is not volume, but provenance, authorization scope, and whether the traffic can be traced back to a specific workload identity or approved automation path.
This term sits close to service-to-service traffic, API traffic, and automated integrations, but it is broader because it includes any non-human origin that can trigger business logic or access sensitive resources. Industry usage is still evolving, so some teams use it narrowly for backend API calls while others include CI/CD jobs, bots, and autonomous NIST Cybersecurity Framework 2.0 and aligns with the governance focus described in Ultimate Guide to NHIs. The most common misapplication is assuming all machine-originated traffic is inherently trusted, which occurs when teams treat network location as proof of identity.
Examples and Use Cases
Implementing controls around machine-to-machine traffic rigorously often introduces routing, attestation, and policy-enforcement overhead, requiring organisations to weigh automation speed against identity assurance.
- Microservices calling one another through authenticated APIs, where each request should be tied to a workload identity rather than a shared key.
- CI/CD pipelines pushing artifacts to registries, which should use short-lived credentials and auditable service identities instead of embedded long-term secrets.
- AI agents invoking tools or retrieval endpoints, where every action needs scope limits and replay-resistant authorization.
- Partner or third-party integrations consuming internal services, which should be segmented and monitored because trust assumptions often degrade across organisational boundaries.
- Scheduled jobs and bots reading or writing records in operational systems, which require clear ownership, rotation, and offboarding of credentials.
These patterns are closely linked to identity governance concerns highlighted in Ultimate Guide to NHIs, and the control logic should map to service authentication guidance in the NIST Cybersecurity Framework 2.0.
Why It Matters in NHI Security
Machine-to-machine traffic becomes a security problem when teams cannot distinguish legitimate automation from compromised credentials, shadow integrations, or overbroad service access. Once that distinction is lost, defenders cannot reliably enforce least privilege, revoke access cleanly, or prove which workload made a sensitive request.
NHIMG research shows that 96% of organisations store secrets outside of secrets managers in vulnerable locations including code, config files, and CI/CD tools, which directly increases the chance that machine traffic is authenticated by compromised material rather than governed identity. The same Ultimate Guide to NHIs also notes that 90% of IT leaders say properly managing NHIs is essential for a successful zero-trust implementation, reinforcing that traffic control and identity control must be designed together. For governance teams, this term matters because machine traffic often crosses internal trust zones faster than human activity and is harder to review manually.
Organisations typically encounter the operational impact only after a leaked API key, suspicious service account activity, or unexpected east-west access exposes how much automation depended on undocumented trust, at which point machine-to-machine traffic becomes operationally unavoidable to address.
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 and risk surface, while NIST CSF 2.0 and NIST Zero Trust (SP 800-207) set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-02 | Covers secret exposure and weak trust around non-human access paths. |
| NIST CSF 2.0 | PR.AA | Identity proofing and authentication apply to automated service access paths. |
| NIST Zero Trust (SP 800-207) | SC-7 | Zero Trust requires per-request access control and segmentation for automated east-west traffic. |
Inventory machine identities, remove exposed secrets, and enforce scoped authentication on every automated call.
