Without identity governance, merger teams lose track of who owns access, which accounts are temporary, and where privileged rights overlap. That creates orphaned access, unresolved segregation-of-duties conflicts, and hidden trust between environments. The result is a larger attack surface and a longer window for misuse during the integration period.
Why This Matters for Security Teams
Acquisition teams usually focus on directory merges, application rationalisation, and user recertification, but identity governance failures often appear first in the non-human layer. Service accounts, API keys, certificates, and machine-to-machine trust links can outlive their original owners and bypass the review processes used for people. That creates hidden privilege, unresolved segregation-of-duties conflicts, and access paths that survive long after the deal closes. Current guidance from NIST Cybersecurity Framework 2.0 is clear that governance must be continuous, not a one-time integration task.
NHIMG’s Ultimate Guide to NHIs and Top 10 NHI Issues both show that unmanaged identities become breach pathways when ownership is unclear and credential lifecycles are not enforced. In acquisition scenarios, that risk expands because two control environments overlap before the target state is defined. In practice, many security teams discover the worst access relationships only after integration starts and service outages or suspicious activity expose them.
How It Works in Practice
Identity governance during an acquisition should start with inventory, ownership mapping, and trust-path discovery across both organisations. The goal is to identify every account, token, certificate, role binding, and system-to-system relationship before those assets are absorbed into the combined environment. That includes temporary accounts created for due diligence, third-party integrations, and automation that no one plans to keep.
A practical approach usually includes:
- Classifying identities by human, privileged, service, and application scope.
- Mapping who owns each identity, where it is used, and what business process depends on it.
- Removing duplicate admin paths and inherited trust that no longer has a business justification.
- Revalidating secrets and certificates so expired or shared credentials do not survive the integration window.
- Applying just-in-time access and least privilege where systems are still being stabilised.
For non-human identities, the issue is not just access review. It is lifecycle control. The lifecycle processes for managing NHIs require consistent provisioning, rotation, monitoring, and revocation, especially when one entity acquires another. That aligns with current industry guidance from NIST CSF 2.0 on governance and risk management, but there is no universal standard for acquisition sequencing yet. The practical objective is to prevent hidden trust from being carried into the combined estate. When merger teams delay identity reconciliation until after network connectivity is opened, inherited service accounts and cross-environment permissions can be exploited before ownership is fully clarified.
Common Variations and Edge Cases
Tighter governance often slows integration, so organisations have to balance speed against the risk of carrying unknown access into production. That tradeoff is especially visible when the target company uses different directory structures, cloud tenants, or automation tooling, because a clean merger is rarely possible on day one.
One common edge case is when the acquired business relies on embedded credentials inside scripts, CI/CD pipelines, or infrastructure-as-code templates. Those identities can be missed by standard user recertification and survive long after human access has been cleaned up. Another is temporary coexistence, where both environments must remain connected for migrations, reporting, or shared operations. Best practice is evolving here: current guidance suggests isolating those trust paths, shortening credential TTLs, and documenting explicit expiry dates rather than allowing indefinite exception handling.
The breach data on 52 NHI Breaches Analysis reinforces a familiar pattern: when ownership is unclear, access persists. The same pattern often shows up in acquisition work where inherited admin rights are left in place “just until the cutover” and never revisited. Organisations that treat identity governance as a post-merger cleanup exercise usually find that the cleanup begins only after an incident or audit exception forces the issue.
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 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Acquisitions create orphaned NHI ownership and undocumented secrets. |
| NIST CSF 2.0 | GV.OV-01 | M&A governance requires oversight of identity risk across both estates. |
| CSA MAESTRO | MAESTRO addresses operational governance for complex, hybrid identity environments. |
Establish merger oversight for identity risk, then track remediation until exceptions are closed.
