How should security teams approach migrating away from legacy IGA systems in complex environments?

Why This Matters for Security Teams

legacy iga systems usually fail in complex environments because they assume identity governance is mostly a workflow problem, when the real issue is an operating model problem. In hybrid estates, teams need consistent joiner-mover-leaver controls, evidence, and approvals across SaaS, cloud, on-premises, and machine identities. That becomes harder when access logic is buried in custom scripts, point-to-point connectors, and manual exceptions.

NHIMG’s Ultimate Guide to NHIs notes that only 5.7% of organisations have full visibility into their service accounts, which is exactly the kind of blind spot that legacy IGA can preserve rather than fix. The security objective is not to preserve old approvals in a new platform, but to reduce standing access, improve auditability, and make identity state provable at scale. That aligns with NIST SP 800-53 Rev 5 Security and Privacy Controls, especially where access review, least privilege, and account management must be enforced consistently.

In practice, many security teams discover that the migration risk is not the target platform itself, but the hidden business dependencies that only appear after an access review fails, a connector breaks, or an offboarding event is missed.

How It Works in Practice

A workable migration starts with a control inventory, not a tooling shortlist. Security teams should map every identity flow that the legacy IGA system touches: human joiner-mover-leaver processes, privileged access, shared accounts, service accounts, API keys, and exceptions handled outside the workflow. The point is to separate what must be preserved from what can be retired. If custom code is doing provisioning, certification, or evidence collection, it should be treated as technical debt with operational risk.

The next step is to define the minimum viable governance model for the target state. That usually means modern connectors, automated provisioning, policy-based approvals, and continuous reconciliation between source-of-truth systems and downstream applications. Where possible, align controls to NIST SP 800-53 Rev 5 Security and Privacy Controls so that access review, account lifecycle, and audit evidence can be demonstrated without manual spreadsheet work. For NHI-heavy environments, the governance baseline should also reflect Ultimate Guide to NHIs, because service accounts and secrets often outlive the application owners who created them.

• Classify every integration by criticality, fragility, and replacement cost.
• Replace brittle custom code with supported connectors or documented APIs.
• Automate provisioning and deprovisioning before moving to broader access certification.
• Preserve audit evidence requirements during the transition so controls remain testable.
• Measure success by reduction in standing access, manual exceptions, and orphaned accounts.

This guidance tends to break down in highly customised ERP, mainframe, and merger-heavy environments because identity dependencies are embedded in business logic that cannot be migrated cleanly in one release.

Common Variations and Edge Cases

Tighter migration controls often increase delivery time and integration cost, so organisations have to balance speed against control fidelity. There is no universal standard for sequencing every legacy IGA retirement, but current guidance suggests that the riskiest areas, such as privileged access, service accounts, and external-facing applications, should move first.

Some environments also need dual-run operation for a period, where the legacy IGA platform and the new governance layer both operate against the same identity sources. That can reduce disruption, but it also creates duplication risk if certification campaigns, approval paths, or revocation logic diverge. In those cases, teams should define a single authoritative source for each identity type and document which system owns provisioning, attestation, and offboarding.

Another edge case is machine identity sprawl. If the legacy IGA tool never modelled API keys, certificates, or workload accounts properly, migration may require a separate remediation programme before governance can be normalised. NHIMG’s research shows how often secrets and service accounts remain invisible or unmanaged, which is why Ultimate Guide to NHIs is relevant during planning, not just after go-live. The practical rule is simple: retire the workflow debt, not just the platform, or the new system will inherit the same exposure with better branding.

Related resources from NHI Mgmt Group

• How should security teams prioritise NHI remediation in cloud environments?
• How should security teams govern non-human identities in cloud environments?
• How should security teams approach TLS migration when legacy systems still depend on older protocol assumptions?
• How should security teams implement visibility-first IGA in complex enterprise environments?