Without an early inventory, inherited accounts, keys, and trust paths remain hidden long enough to be abused during integration. The result is delayed deprovisioning, unresolved ownership, and privileged access that survives the deal closure. In practice, this creates a blind spot where attackers can move faster than governance can reconcile the estate.
Why This Matters for Security Teams
M&A activity turns identity sprawl into an immediate risk because the acquired environment usually contains service accounts, API keys, certificate chains, and third-party trust paths that are not visible to the buyer on day one. When those inherited identities are missed, teams cannot decide what to keep, rotate, revoke, or monitor, so integration proceeds with unresolved privilege. That is especially dangerous for non-human identities, where one forgotten credential can outlive multiple human owners.
NHI Management Group’s Ultimate Guide to NHIs notes that only 5.7% of organisations have full visibility into their service accounts, which explains why post-deal identity inventories so often start too late. The broader risk is not just access leakage but governance failure: teams inherit accounts they do not know exist, and attackers only need one valid path to begin lateral movement. This aligns with the visibility and asset-management emphasis in NIST Cybersecurity Framework 2.0.
In practice, many security teams discover the hidden identities only after integration has already expanded the blast radius and the original owners are no longer available.
How It Works in Practice
An early inventory is the control that turns an unknown inherited estate into an actionable one. The first pass should identify every non-human identity, where it is used, who can approve its use, what it authenticates to, and whether it depends on embedded secrets, federated trust, or long-lived certificates. That means reviewing code repositories, CI/CD pipelines, cloud subscriptions, vaults, secrets stores, SSH keys, OAuth apps, certificate authorities, and partner integrations before systems are merged.
Teams usually get better results when they classify each identity into one of four actions: retain, rotate, replace, or remove. Retain applies to business-critical identities with a named owner. Rotate applies when the account is valid but trust is uncertain. Replace applies when the identity is tied to legacy tooling that should be refactored. Remove applies when the identity has no clear business purpose or cannot be mapped to an accountable owner. The baseline control objective is straightforward: no inherited identity should remain active without documented ownership and an expiry plan.
Practitioners should also connect the inventory to change management and access reviews, not treat it as a one-time spreadsheet exercise. This is where current guidance from CISA identity and access management guidance is useful: visibility must feed revocation and least-privilege enforcement, or it becomes documentation without risk reduction. NHI Management Group’s JetBrains GitHub plugin token exposure illustrates how a single exposed token can persist well past the event that created it, which is exactly why acquisition inventories need immediate secret discovery and ownership mapping.
- Start with discovery across source control, vaults, cloud IAM, and CI/CD systems.
- Map each inherited identity to a business service and an accountable owner.
- Tag identities by privilege level, external exposure, and rotation status.
- Revoke or rotate credentials before integration cutover where feasible.
- Record exceptions with a time-bound remediation plan.
These controls tend to break down when the acquired company has unmanaged developer tooling and undocumented machine-to-machine trust chains, because the inventory cannot be trusted to be complete.
Common Variations and Edge Cases
Tighter inventory controls often slow integration timelines, requiring organisations to balance transaction speed against the risk of inheriting active abuse paths. That tradeoff is real, especially when the deal team wants rapid platform consolidation and the security team still lacks asset-level visibility. Current guidance suggests prioritising the highest-risk identities first rather than waiting for a perfect complete inventory.
There is no universal standard for how deep the first-pass inventory must go, but best practice is evolving toward credential discovery, trust-graph mapping, and owner validation before Day 1 integration activities. Some environments also introduce temporary containment, such as network segmentation or conditional access, when immediate revocation would disrupt revenue-critical services. In regulated sectors, the inherited identity review should be tied to audit evidence so that exceptions are not lost after legal close.
The biggest edge case is a carve-out or partial acquisition, where inherited identities may straddle both organisations for months. In that situation, unresolved trust paths can remain active even if the acquired systems are decommissioned, because third-party integrations, certificates, and shared automation may still point back to the old estate. That is why acquisition inventories need to include dependent systems, not just direct logins, and why organisations should treat inherited secrets as an integration blocker until ownership is explicit.
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 AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Inventory and visibility failures drive hidden inherited identities and secrets. |
| NIST CSF 2.0 | ID.AM-1 | Asset management is essential when M&A introduces unknown identities and trust paths. |
| NIST AI RMF | GOVERN | M&A identity governance needs accountable oversight and documented risk decisions. |
Build a complete NHI inventory before integration and attach an owner, purpose, and rotation state to each item.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on June 23, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
