Single Sign-On Testing: A Step-by-Step Guide

As one of the most commonly used and trusted forms of digital security authentication, SSO (Single Sign-On) is an essential element of most applications that require users to sign in. SSO allows users to access multiple apps with a single set of credentials, which heavily boosts user experience and convenience without composing any security standard.

SSO is implemented using authentication protocols such as OAuth 2.0, SAML, or OpenID Connect.

Just like every application feature requires testing, so does the SSO implementation. This article will provide an in-depth exploration of this specialized area — SSO testing. It is intended to serve as a foundational introduction to the comprehensive field of SSO testing methodologies.

What Is SSO testing?

SSO testing involves verifying the functionality, security, and performance of the SSO mechanism, ensuring users can access multiple services with a single set of credentials. The most common example is the SSO integration for Gmail in multiple applications; you can sign up and then sign in via your email credentials, without needing another ID and password. 

SSO testing verifies that the single sign-on functionality works seamlessly across diverse devices, OSes, browsers, and platforms. 

Steps Involved in an SSO Test

• Functionality tests to ensure that the SSO integration functions as expected across all required applications. 
• Security tests to ensure that SSO mechanisms handling private credentials guard the data from unauthorized access. Check for common threats like replay attacks and end-to-end data encryption. 
• Performance tests to evaluate how the SSO function works under different conditions. Login time and system response rates are important metrics. 
• Compatibility tests to ensure that the SSO functions well across different browsers, devices and OSes. 
• Error handling tests to check system response to failed attempts, network glitches, server issues, and the content of the error messages. 

Additional Steps

• Defining test scenarios based on user roles, system interactions, and authentication flows. Expect edge cases to cover all bases. 
• Creating dedicated test environments that simulate production conditions, incorporating all integrated applications, authentication protocols, and configuration settings.

How to Test SSO Authentication 

SSO testing scenarios generally cover three phases:

• The actual SSO process
• The post-authentication stage
• The post-logout stage

The Actual SSO Process

To log in via SSO, you must validate two applications — a service application for which you want to log in and an authenticating application for which you need to enable the authentication required for signing in. 

When a user tries to log in, the server app calls the authenticating app to verify user credentials. Test the data exchange between these two on certain metrics. 

Encryption

The data exchange between the two applications must be protected as it contains sensitive information. It should be guarded against sniffing, MITM, and other methods hackers use to steal data. Test data encryption using network interception tools such as Wireshark or Burp Suite. Simulate various network scenarios and monitor for data leakage or the presence of unencrypted sensitive information.

Valid Login Data

To authenticate the user, the authentication engine requests relevant details — an email address, first and last name, date of birth, and the like. Data requests and responses occur through APIs. If invalid data is used, the program will crash, or the sign-in will not proceed. 

Test if the right data is being requested and if the program returns valid responses. 

Once the data is retrieved, you must test if it has the right impact — signing the user into the service application. If the data is valid, the SSO should proceed. If the data is invalid, there’s no [point even testing the SSO because their datasets are the problem.

A common example is that the email address used during the SSO process should be the same as the email in the service application. Simply create a set of valid and invalid data, and use them to test the SSO. If the sign-in goes through with the valid data and fails with the invalid, it works exactly as intended. Any other response is cause for concern. 

Server Status and Operations

Check server performance to ensure that the data exchanges between the service and auth application remain fast and concise. Does the server work as expected before and after the actual login? Is the process easy and fast?

Beware of any batches of unoptimized code that could lead to unnecessary delays and pauses. 

The Post-Authentication Stage

When you test SSO mechanisms, don’t forget that the process doesn’t necessarily “end” with successful user authentication. Technically, it does, but its effect continues post-authentication. 

Since SSO occurs automatically, QAs must check that the process doesn’t change or break any core functions or UI elements after authentication. 

Role-Based Access and Capabilities

Depending on the application, an authenticated user should have access to the right features after login. 

Certain applications restrict access based on a user’s security clearance. Once users log in using their credentials, the application should automatically allow them access to the right features and privileges. Normal users shouldn’t be able to utilize features or trigger actions meant for users with privileged access, and SSO tests must check for this.  

Note: It is possible to run manual tests in which you sign in with different IDs and passwords. However, it’s easier if you automate such redundant tasks via automation tools (more on that later). 

Write and run tests to detect broken authentication flows — something quite common in apps supporting SSO. Also, check if the default access can be manipulated. 

After sign-in, regular users should be sent to the */home.php page. Admins, on the other hand, should be directed to the */admin.php page. Test if, in any scenario, a normal user is directed to the admin page and its privileges by changing the URL.

Timeouts

SSO authentication sessions have expiration periods for security purposes. After the user has been authenticated and logs in, the authentication mechanism expires after a specific duration. Check if the session timeouts function correctly and expire as expected after the user is logged in. Improper timeouts are an inevitable security threat. 

The Post-Logout Stage

Once a user logs out, they should lose all access to the service application’s features until they log back in again. They shouldn’t be able to run any actions or use any features. 

Check this by logging out and trying to use the application features again. If it’s possible, your app is carrying a massive security risk and will actively harm users. 

Generally, bugs like this emerge from unsatisfactory logout management and coding practices or improper SSO implementation. 

SSO Authentication Test Cases

• Login Tests: Verify that users can log in with valid credentials and that they cannot log in with invalid details. Both scenarios are essential test cases. In both cases, the system throws the relevant messages (success in the first scenario and error in the second).
• Timeout Tests: Does the SSO session expire after the right window of time? Do users have to re-authenticate to log back in?
• Password Changes: If a user changes their password, is the information updated across all linked applications? If not, the SSO mechanism does not work fundamentally.
• Role and Access Tests: Check that user logins match permissions and grant them access to features based on their privileges. Their credentials should map them to the specific features they need.
• Cross-Browser Compatibility Tests: Verify that the SSO implementation works flawlessly and consistently across different web browsers.
• Network Connectivity Tests: Verify that the SSO system handles network disconnections and connectivity drops appropriately.
• User Experience Tests: Verify that the usage and speed of the SSO protocol is equally user-friendly across different platforms.       

Conclusion

SSO testing ensures secure, functional, and user-friendly authentication systems, balancing convenience with security. As protocols evolve and threats emerge, SSO testing must adapt. Comprehensive testing helps organizations provide seamless access while maintaining strong security, fostering trust in a complex online ecosystem.