They often treat service accounts and API keys as secondary to human identities, even though those machine accounts can retain broad access across inherited systems. They also underestimate ownership gaps, which means orphaned credentials survive the transaction. In practice, NHI governance must be built into due diligence and separation planning, not added after human account migration is complete.
Why This Matters for Security Teams
In M&A, nhi governance is often misread as a routine identity inventory exercise, but that framing misses the real risk: inherited machine access can outlive the transaction logic that created it. Service accounts, API keys, tokens, and certificates may cross trust boundaries with broad permissions, hidden dependencies, and unclear owners. That creates immediate exposure in separation planning, clean room design, and Day 1 cutover.
The mistake is assuming human identity controls will naturally extend to machine identities. They rarely do. Human account migration can be tracked in HR and IAM workflows, while NHIs often sit inside applications, automation pipelines, and third-party integrations with weak provenance. NHI management needs to be part of diligence, not a post-close remediation item. NHI Management Group’s Top 10 NHI Issues highlights ownership and lifecycle gaps as recurring failure points, which aligns with broader control guidance in the NIST Cybersecurity Framework 2.0.
One useful signal: NHI Management Group cites research showing only 1.5 out of 10 organisations are highly confident in their ability to secure NHIs, compared with nearly 1 in 4 for human identities. In practice, many security teams discover the gap only after inherited systems are already connected, not during the transaction planning that should have exposed it.
How It Works in Practice
Effective M&A NHI governance starts with identifying every machine identity that will be acquired, retained, migrated, or retired. That includes application accounts, CI/CD secrets, OAuth grants, certificates, service principals, and embedded credentials in scripts or configuration stores. The goal is not only to list them, but to map each NHI to a business service, a technical owner, a privilege scope, and a likely post-close fate.
Current guidance suggests three practical steps. First, add NHI discovery to carve-out and target-state diligence so the acquiring team can see where authentication is happening and where secrets are stored. Second, classify each NHI by criticality and exposure, then decide whether it should be re-issued, rotated, scoped down, or terminated during separation. Third, build revocation into the cutover plan so orphaned access does not survive handover. The Ultimate Guide to NHIs — Lifecycle Processes for Managing NHIs is helpful for translating that lifecycle view into operational tasks, while the 52 NHI Breaches Analysis shows why undiscovered credentials remain a recurring breach pattern.
A simple implementation checklist often helps:
- Require NHI inventories in due diligence questionnaires and TSA planning.
- Tag each machine identity with owner, system, expiry, and migration status.
- Rotate or replace shared secrets before connectivity is extended across entities.
- Use least privilege and time-bound access for transitional integrations.
- Validate that logging, alerting, and revocation still work after directory and network changes.
These controls tend to break down when the acquired environment is heavily automated and poorly documented because ownership cannot be verified fast enough to support separation deadlines.
Common Variations and Edge Cases
Tighter NHI control often increases deal friction and operational overhead, so organisations must balance transaction speed against the cost of leaving inherited access in place. That tradeoff is especially sharp when shared infrastructure, outsourced operations, or legacy middleware make it difficult to isolate machine identities cleanly.
There is no universal standard for this yet, but best practice is evolving toward treating some NHIs as deal-critical assets that require explicit sign-off before close. In regulated environments, that can mean preserving evidence of control decisions for audit and post-close assurance. The Ultimate Guide to NHIs — Regulatory and Audit Perspectives is a practical reference for that documentation mindset.
Edge cases often include M&A deals where identity data is incomplete, where SaaS integrations are hidden behind business-owned admin accounts, or where the target company uses vendor-managed automation with no internal owner. In those cases, the safest assumption is that any unknown secret is active until proven otherwise. The right answer is not to delay all integration work, but to sequence it so machine identity discovery, rotation, and revocation are completed before broad trust is extended across the combined estate.
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 and CSA MAESTRO address the attack and risk surface, while NIST CSF 2.0 and NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | M&A often exposes unknown NHIs and weak ownership across inherited systems. |
| NIST CSF 2.0 | ID.AM-1 | Asset inventory is central when inherited machine identities are hidden in acquisitions. |
| NIST AI RMF | Governance and accountability apply to autonomous machine access decisions in M&A. | |
| CSA MAESTRO | MAESTRO addresses governance for complex agentic and machine access ecosystems. |
Use lifecycle controls to discover, constrain, and retire machine identities during integration.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on August 25, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
