How to Integrate IAM with Custom-Built Applications

It is easy to integrate IAM with popular applications. Most of them support SSO out of the box. But what if you have applications that you developed internally?

These applications often have their own login mechanisms, user databases, and authorization rules.

Let’s explore how IAM integration with custom applications works, including the integration methods, implementation steps, challenges, and security practices you need to consider.

Why Integrate IAM with Custom-Built Applications?

While you can maintain a separate authentication flow for your custom applications, it will add complexity as your organization grows.

You can simplify this by integrating your custom applications with your Identity and Access Management (IAM) platform and addressing three other common challenges.

1. Centralize Authentication Across Applications

Without centralized authentication, users will have to remember different passwords, and you will have to manage authentication settings for multiple applications.

Connecting all applications to a central Identity Provider (IdP) allows users to sign in through the same identity infrastructure. You manage a single identity directory.

2. Apply Consistent Access Policies

You can enforce policies, such as user or group assignment, Multifactor Authentication (MFA), and contextual access requirements, globally from a centralized dashboard. Your custom applications will receive the same level of security as others.

3. Reduce Application-Specific Credentials

Separate login systems create more credentials to manage. When this happens, employees tend to reuse credentials. Or you might miss an account during offboarding.

With SSO, users authenticate through a configured IdP instead of signing in separately to every connected application. This reduces the need for application-specific passwords, as federated authentication replaces the local login.

IAM Integration Methods for Custom Applications

There are multiple IAM integration methods. Some protocols handle user authentication and SSO. Others handle delegated access to protected resources. Let’s compare them:

Steps to Integrate IAM with a Custom Application

The following steps cover a typical federated SSO integration, although the exact configuration will vary by protocol and application.

Step 1: Assess Your Application Architecture and Authentication Requirements

Find out the following details about your application:

• Application type: Is it a server-side web application, single-page application, mobile app, or API?
• Current authentication: Does it use local passwords, LDAP, an existing IdP, or another mechanism?
• Protocol support: Does it support SAML, OIDC, or another standard? Can you modify its authentication code?
• Authorization model: Does the application use roles, groups, permissions, or resource-level policies?
• Session behavior: How does it create sessions, expire them, and handle logout?
• User population: Will employees, contractors, customers, or external partners sign in?

This will help you determine the integration method.

Also, identify whether you need only SSO or additional capabilities such as MFA, automated provisioning, and account deactivation, as they need separate configuration.

Step 2: Select the Appropriate Protocol

Choose a protocol that both the application and the IdP can support.

Use SAML 2.0 if your application supports SAML-based enterprise SSO. Choose OIDC if you need federated user authentication in a modern application. Use OAuth 2.0 when clients need delegated access to APIs and protected resources.

If your application uses LDAP or Active Directory, determine whether directory-based authentication meets your requirements or whether you need a federation layer to provide SSO.

Step 3: Register the Application with Your Identity Provider

Create an entry in your IAM platform to establish a trusted relationship.

The provider uses this configuration to identify the application and establish the trust relationship required for authentication.

The details depend on the protocol:

• SAML: Configure the service provider's Entity ID and ACS URL. Obtain the IdP metadata and signing certificate.
• OIDC: Configure the client ID, allowed redirect URIs, issuer, and required client authentication settings.
• OAuth 2.0: Register the client, define the relevant authorization flow and redirect URIs where applicable, and configure scopes and resource access.

For OIDC and OAuth, choose the correct client type. A confidential server-side client can protect a client secret, while a public client cannot reliably keep a shared secret confidential.

Step 4: Configure Endpoints, Redirect URIs, Certificates, and Credentials

Your application must know where to send authentication requests and how to process the response. Your IdP must know which application is making the request and where it can return the response. So you have to configure:

• Authentication, authorization, and token endpoints where applicable.
• Exact redirect URIs or the SAML ACS URL.
• Issuer identifiers, Entity IDs, and audience values.
• SAML signing certificates and metadata.
• Client IDs and securely stored client secrets or certificate credentials.
• Required scopes and approved redirect locations.

For production deployments, use HTTPS for relevant endpoints and callbacks, protect private keys and secrets, and establish a process for certificate and credential rotation.

Step 5: Map User Attributes and Application Roles

Review the user attributes returned by your IdP. These typically include a unique user identifier, email address, name, and group and role claims.

Map those attributes to the fields your application expects. Confirm that the identifier is stable and unique within the intended user population.

Next, define how users receive application roles and permissions. Do not assume that an authenticated user is automatically authorized to access every feature. Also, avoid granting administrative privileges simply because a user belongs to a broad organizational group.

Step 6: Test Authentication, Authorization, and Logout

Verify logins. More importantly, test your session termination flows. Include successful and unsuccessful scenarios.

Test the browser redirects and callback handling as well. For OIDC, verify that the flow validates transaction state and uses the required protections, such as PKCE and nonce checks where applicable.

Step 7: Monitor Authentication Logs and Access Failures

After deployment, monitor the integration for failed sign-ins, rejected responses, expired certificates, incorrect claims, and authorization failures.

Review logs from both the identity provider and the application. Together, they can help you distinguish an authentication failure from an application-level permission problem.

Track recurring errors and investigate unexpected access patterns. Establish a process for reviewing changes to application registrations, redirect URIs, certificates, credentials, and role mappings.

If you also implement automated provisioning, monitor provisioning failures and deprovisioning events separately. Successful SSO does not prove that an application's user accounts and access assignments are up to date.

Common IAM Integration Challenges

Even when your application supports a standard protocol, integration can uncover issues that require changes to its configuration or code.

Applications Without Native SAML or OIDC Support

You cannot connect older applications that do not have native SAML or OIDC support.

Review the application's extension points and supported connectors. Depending on the environment, you may need to modify the application or use a compatible authentication proxy or adapter. Confirm that the chosen approach actually supports your application's login flow and security requirements.

Inconsistent User Attributes and Role Mappings

Elements like attribute names, user identifiers, or role structures might not be the same between your application and the IdP. Make sure they are mapped correctly during implementation, and test how the application handles missing or unexpected claims.

Session Management and Logout Issues

The IdP and application maintain separate session state. A user may sign out of the application while the IdP session remains active or vice versa.

Test each flow with your specific protocol and application framework.

Legacy Authentication Dependencies

Some legacy applications depend on authentication mechanisms that do not directly support modern federation protocols. These dependencies can complicate SSO and may require an intermediary integration.

Best Practices for Secure IAM Integration

Once you have a working integration, you must validate authentication responses, protect credentials, and enforce the right permissions.

• Use standard authentication protocols instead of creating a custom authentication exchange.
• Enforce least-privilege access and review both IdP assignments and application-level authorization rules.
• Verify signatures, issuers, audiences, expiration, and other protocol-specific requirements.
• Store secrets in a credential management system and establish rotation and renewal policies.
• Record relevant authentication outcomes, access failures, and administrative configuration changes.

Connect Your Custom Applications with miniOrange IAM

Integrating custom applications with IAM gives you greater control over authentication without requiring every application to manage sign-ins independently. It maintains the distinction between verifying a user's identity and deciding what that user can access.

miniOrange IAM is built to easily connect with custom-built, enterprise, and SaaS applications through SSO using SAML, OAuth, OpenID Connect, and WS-Federation. You can also strengthen authentication with MFA and manage supported user provisioning and role-based access control through SCIM and RBAC.

FAQs

How do you integrate SSO into a custom application?

Start by checking which authentication protocols your application supports. Register the application with your IdP, configure the relevant endpoints and credentials, map user attributes and roles, and test the complete sign-in flow before deployment.

Which IAM protocol is best for custom applications?

There is no single protocol for every application. SAML 2.0 is suitable for compatible enterprise SSO integrations, while OIDC supports federated user authentication in modern applications. OAuth 2.0 handles delegated authorization, and LDAP or Active Directory can support applications that integrate directly with directory services.

Can IAM integrate with applications that do not support SAML or OIDC?

Yes, in some environments, but the approach depends on the application's authentication mechanism and available integration options. You may need to modify the application or use a compatible connector, proxy, or adapter. Verify that the proposed solution supports the application before committing to an implementation.