The Proliferation of Shadow IT
In the modern corporate environment, employees rely on dozens of different SaaS (Software as a Service) applications daily—from Salesforce and Slack to Zoom and Asana. If employees are allowed to create their own usernames and passwords for each of these services, IT loses all control. This is known as “Shadow IT.”
If an employee is terminated, IT must manually log in to 15 different applications to revoke their access. If they miss even one (such as a third-party CRM), the former employee retains access to highly sensitive corporate data.
To eliminate this risk, organizations must centralize authentication using Single Sign-On (SSO). If your organization uses Google Workspace for email and document collaboration, you already possess a powerful, enterprise-grade Identity Provider (IdP). By leveraging the SAML 2.0 (Security Assertion Markup Language) protocol, you can configure Google Workspace to authenticate your users across nearly any third-party application.
Step 1: Understanding the SAML Handshake
Before configuring the system, you must understand the architecture of SAML. There are two primary actors:
- The Identity Provider (IdP): This is Google Workspace. It holds the user credentials, enforces Multi-Factor Authentication (MFA), and issues the cryptographic “Assertion” proving the user’s identity.
- The Service Provider (SP): This is the third-party application (e.g., Zoom). It does not store passwords. It simply trusts the Assertion sent by Google.
When a user tries to log in to Zoom, Zoom redirects their browser to Google. The user logs in to Google (passing MFA). Google then redirects the browser back to Zoom, carrying an encrypted XML payload (the Assertion) that says, “I am Google. I verify this is John Doe, and his email is [email protected].” Zoom reads the XML, validates the cryptographic signature, and logs John in.
Step 2: Preparing the Service Provider (SP)
To establish the trust relationship, you must exchange configuration details between Google and the third-party app.
Log in to the third-party application as an administrator and locate its SSO or SAML configuration page. You will need to gather two critical URLs from the application:
- ACS URL (Assertion Consumer Service): The exact URL where Google must send the XML payload after a successful login.
- Entity ID: A unique string that identifies the application to Google.
Step 3: Creating the Custom SAML App in Google Workspace
Now, you must configure Google to act as the Identity Provider for this specific application.
- Log in to the Google Workspace Admin Console (admin.google.com).
- Navigate to Apps > Web and mobile apps.
- Click the Add app dropdown and select Add custom SAML app.
- Name the application (e.g., “Corporate Zoom”) and upload a logo for the user dashboard.
- Download the IdP Metadata: Google will provide an option to download the IdP Metadata XML file (or manually copy the SSO URL and the X.509 Certificate). This is Google’s public key that you will give to the third-party app so it can verify the signatures.
- Input the SP Details: In the next screen, paste the ACS URL and Entity ID you gathered from the third-party app in Step 2.
- Attribute Mapping: SAML relies on mapping fields. By default, map the “Primary Email” in Google to the “NameID” in the application. This ensures the app knows exactly which user account to log into.
Click Finish to save the application.
Step 4: Completing the Trust on the Service Provider
Return to the third-party application’s administration console. You must now upload the IdP Metadata XML file (or paste the X.509 certificate) that you downloaded from Google.
Once you save this configuration in the third-party app, the cryptographic trust is fully established. Google knows where to send the authentication payload, and the application knows how to verify Google’s signature.
Step 5: Provisioning User Access
By default, when you create a new SAML app in Google Workspace, it is turned OFF for everyone. If a user tries to log in, Google will block the attempt and display a 403 App_Not_Configured error.
To grant access:
- In the Google Admin Console, go back to Apps > Web and mobile apps and click on your newly created app.
- Click on User access.
- You can turn it ON for everyone, or selectively enable it for specific Organizational Units (OUs) or Groups (e.g., only enabling Salesforce for the Sales OU).
Conclusion
Configuring SAML SSO via Google Workspace is the single most effective action an IT department can take to secure corporate data. By centralizing authentication, you eliminate password fatigue, enforce Phishing-Resistant MFA across every application simultaneously, and guarantee that when an employee’s Google account is suspended, their access to all third-party services is instantly revoked.