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Identity Authority
Category: Cloud Identity

Hybrid Identity

Simply put

Hybrid identity is an approach that lets an organization use one set of user identities across both its on-premises systems and cloud services. Instead of maintaining separate accounts in each environment, users have a common identity that works in both places. This is typically achieved by connecting traditional on-premises directories to cloud identity providers.

Formal definition

Hybrid identity is an architecture in which on-premises identity services (such as directory infrastructure) are integrated with cloud identity providers and SaaS applications to establish a common user identity usable for both authentication and authorization across on-premises and cloud environments. In most deployments this involves synchronizing or federating on-premises directory identities with a cloud identity provider so that a single identity can be used to verify a user (authentication) and determine their permitted access (authorization) in both domains. The specific mechanisms, synchronization models, and enforcement points vary by vendor and deployment configuration; note that this term refers to the identity-infrastructure sense and is distinct from the unrelated social-science usage describing an individual's integration of multiple cultural or social identities.

Why it matters

Most organizations do not operate exclusively on-premises or exclusively in the cloud; they run a mix of legacy directory-bound applications and modern SaaS services. Hybrid identity matters because it lets a single user identity serve for both authentication and authorization across both domains, which reduces the operational burden and security risk of maintaining separate, unsynchronized accounts in each environment. Fragmented identity, where a user exists as distinct accounts in different systems, makes lifecycle events such as onboarding and offboarding harder to execute consistently and can leave orphaned access behind.

Because hybrid identity spans the boundary between on-premises directory infrastructure and cloud identity providers, it becomes a critical piece of an organization's attack surface. The synchronization or federation link between the two environments is itself a component that must be secured, monitored, and correctly configured; misconfiguration or compromise at that junction can affect trust across both domains simultaneously. Guidance such as CISA's Hybrid Identity Solutions Guidance exists precisely because addressing identity management across a hybrid environment requires deliberate architectural choices rather than incidental integration.

The stakes are also governance-related. When one identity grants access in both on-premises and cloud contexts, organizations need clear visibility into where that identity's access is enforced and how it is provisioned, so that access reviews and segregation-of-duties controls remain meaningful across the combined estate. The specific risks and controls depend heavily on the chosen synchronization model, vendor, and deployment configuration.

Who it's relevant to

Security Architects
Architects designing systems that span on-premises and cloud environments must decide how identities are synchronized or federated between directory infrastructure and cloud identity providers. They own the trade-offs among synchronization models and are responsible for securing the integration link that connects the two domains.
IAM Engineers
Engineers implement and operate the connections between on-premises directories, cloud identity providers, and SaaS applications. They configure the synchronization or federation mechanisms that make a single identity usable for authentication and authorization across both environments, with behavior depending on vendor and deployment specifics.
Identity Governance Leads
Governance leads need consistent visibility into access granted by a common identity across both on-premises and cloud contexts. Hybrid identity affects how access reviews, certification, and segregation-of-duties controls are applied so that governance remains coherent across the combined estate.
Compliance Officers
Compliance officers assess whether identity management across a hybrid environment meets applicable control requirements. Guidance such as CISA's Hybrid Identity Solutions Guidance can inform how they evaluate the risks and configurations associated with spanning on-premises and cloud identity services.
System Administrators
Administrators manage day-to-day operations of accounts that exist across both on-premises and cloud systems. Hybrid identity reduces the need to maintain separate accounts per environment, but it also requires them to understand where identity data originates and how changes propagate between domains.

Inside Hybrid Identity

On-premises directory
A local identity store, commonly an LDAP directory or an on-premises directory service, that holds accounts, groups, and attributes for the organization's traditional environment. In a hybrid identity model this directory is one of the authoritative sources that must be reconciled with cloud-based identity systems.
Cloud identity provider
A cloud-hosted IdP that issues assertions or tokens for cloud and SaaS applications. Depending on configuration it may authenticate users directly or rely on federation back to the on-premises directory.
Directory synchronization
The process of replicating identity objects and attributes between on-premises directories and the cloud identity provider so that a consistent representation of principals exists across environments. Synchronization scope, direction, and attribute mapping vary by deployment and tooling.
Federation
A trust relationship that lets one environment accept authentication assertions from another, typically implemented with SAML 2.0 for web SSO or with OpenID Connect (the authentication layer built on OAuth 2.0). Federation allows a cloud service to defer authentication to the on-premises IdP rather than duplicating credential verification.
Provisioning and lifecycle (IGA)
Identity governance and administration concerns such as provisioning, deprovisioning, access reviews, certification, and segregation of duties that must span both on-premises and cloud targets. SCIM is commonly used to provision and deprovision accounts to cloud applications. These lifecycle activities are distinct from runtime access enforcement.
Authentication method integration
The mechanisms that determine how and where a principal is authenticated across environments, which may include MFA, step-up authentication, or passwordless options such as FIDO2/WebAuthn passkeys. In hybrid models the authentication step may occur on-premises, in the cloud, or be delegated via federation depending on configuration.

Common questions

Answers to the questions practitioners most commonly ask about Hybrid Identity.

Does hybrid identity mean my on-premises directory and cloud identity provider are automatically the same authoritative source?
No. Hybrid identity refers to an architecture that spans on-premises and cloud identity systems, but it does not by itself establish a single authoritative source. In most deployments one system is designated as the source of truth (commonly the on-premises directory) and identities are synchronized or provisioned to the other. Which system is authoritative for which attributes depends on configuration, and it is possible to have different authoritative sources for different attributes or object types.
Is hybrid identity just about synchronizing passwords between on-premises and cloud systems?
No. Password synchronization is only one possible authentication approach within a hybrid identity architecture, and it is distinct from the broader scope of hybrid identity. Depending on configuration, authentication may instead be handled through federation (for example SAML 2.0 or OIDC) or delegated back to the on-premises system, while synchronization may cover many attributes beyond credentials. Hybrid identity also encompasses provisioning, governance, and authorization concerns that are separate from how credentials or authentication are handled.
How should I decide between federated authentication and directory synchronization for a hybrid deployment?
The choice depends on where you want authentication to be performed and validated. Federation typically keeps authentication with the on-premises or designated identity provider and returns assertions or tokens to the relying system, which can be useful when you need to retain full control over the authentication event. Synchronization-based approaches may replicate credential material or hashes so the cloud system can authenticate directly, which can reduce dependence on on-premises availability. Many organizations weigh availability, control over the authentication step, and operational complexity, and some deploy both with one as a fallback depending on configuration.
How do provisioning and deprovisioning typically work across a hybrid identity environment?
Provisioning across hybrid environments is generally an identity governance and administration (IGA) concern rather than a runtime enforcement one. In most deployments a lifecycle process creates and updates accounts in the authoritative system, and changes propagate to connected systems through synchronization or a provisioning protocol such as SCIM. Deprovisioning behavior varies by configuration and connector, and gaps between systems are a common source of orphaned accounts, so validating that disable and delete actions propagate consistently is important.
What happens to authentication if connectivity between on-premises and cloud is lost?
The impact depends on which authentication approach is configured. If authentication is federated to or delegated back to an on-premises component, loss of connectivity can prevent users from authenticating to cloud-facing applications. If credentials or hashes are synchronized so the cloud system can authenticate independently, authentication may continue for those systems while on-premises-only resources are affected. Assessing these failure modes and considering fallback authentication paths is a common part of hybrid design.
How should segregation of duties and access reviews be handled when identities span multiple systems?
Because access may be granted in both on-premises and cloud systems, governance controls such as segregation of duties and access certification generally need visibility across both. In most deployments this requires aggregating entitlements from each connected system into a governance platform so reviewers can evaluate combined access. These are IGA lifecycle controls and are distinct from runtime enforcement; effectiveness depends on how completely entitlements are collected from each system and how consistently the authoritative source is maintained.

Common misconceptions

Hybrid identity means all authentication happens in the cloud once directories are synchronized.
Directory synchronization replicates identity data, but where authentication actually occurs depends on the deployment. In federated configurations the cloud provider defers the authentication step back to the on-premises IdP, while other configurations authenticate against synchronized credentials in the cloud. Synchronizing objects is not the same as choosing an authentication path.
Synchronizing accounts to the cloud is sufficient to govern access across the hybrid estate.
Synchronization is a provisioning and data-consistency mechanism, not a governance control. Identity governance concerns such as access reviews, certification, and segregation of duties, as well as runtime enforcement through a PDP/PEP, are separate functions that must be addressed independently of whether directory objects are replicated.
Federation and provisioning are interchangeable ways to connect on-premises and cloud identity.
Federation establishes a runtime authentication trust (for example via SAML 2.0 or OpenID Connect) so a service can accept assertions, whereas provisioning (often via SCIM) creates and maintains the account and attribute records in the target ahead of or independent of sign-in. They address different problems and are frequently used together rather than as substitutes.

Best practices

Define an authoritative source for each identity attribute and document the synchronization direction and attribute mapping between the on-premises directory and the cloud identity provider to avoid conflicting or stale data.
Decide explicitly where the authentication step occurs for each application, distinguishing federated authentication that defers to the on-premises IdP from cloud-based authentication, and record the trade-offs of each configuration.
Keep identity governance activities such as provisioning, deprovisioning, access reviews, certification, and segregation of duties consistent across both on-premises and cloud targets rather than governing each environment in isolation.
Use standards-based connectors where possible, such as SAML 2.0 or OpenID Connect for federation and SCIM for provisioning, and confirm the specific profiles supported by each vendor before relying on a claimed capability.
Apply MFA and, where appropriate, step-up authentication consistently across hybrid access paths so that authentication assurance does not depend on which environment a user enters through.
Validate that synchronized and federated flows fail safely, ensuring that deprovisioning in the authoritative directory propagates to cloud targets in a timely manner and that token validation and trust configurations are reviewed regularly.
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