Microsoft Single Sign On
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Lets you sign in to supported websites with your Microsoft work or school accounts on Windows and macOS platforms, streamlining access to a wide range of services including Office Online and OneDrive. Suitable for individuals using Microsoft accounts for personal or professional purposes, this extension simplifies the login process across various websites. Benefits most those who frequently use Microsoft services online.
Overview
Use this extension to sign in to supported websites with Microsoft work or school accounts on Windows (10 and later versions) or macOS (11 and later versions). If you have a Microsoft Entra ID on your Windows or macOS computer, this extension enables improved Single Sign On for supported websites. You may still see additional authentication prompts like multi-factor verification depending on the access requirements for various applications, resources, and organizations.
This extension is required for certain device-based conditional access policies for Microsoft Entra ID. https://learn.microsoft.com/en-us/entra/identity/conditional-access/concept-conditional-access-conditions#supported-browsers
For macOS, this extension requires the device to be managed and requires the additional installation of Company Portal: https://learn.microsoft.com/en-us/mem/intune/user-help/enroll-your-device-in-intune-macos-cp
Note: If you are experiencing difficulties with signing in or accessing resources, it could be related to your organization’s device policies. Please submit a support ticket directly to Microsoft through your tenant’s subscription. The developer email address for the extension is not an avenue for customer support.
Tags
Privacy Practices
Security Analysis — Microsoft Single Sign On
Permissions
Code Patterns Detected
External Connections
What This Extension Does
The Microsoft Single Sign On extension enables users with Microsoft work or school accounts to seamlessly sign into supported websites using their existing authentication credentials. It is designed for enterprise environments where Microsoft Entra ID (formerly Azure AD) is used, and it supports conditional access policies that require browser extensions on Windows and macOS devices. This extension primarily serves organizations managing device-based security through Microsoft's identity platform.
Permissions Explained
- nativeMessagingexpected: This permission allows the extension to communicate with native applications installed on your computer, such as system-level tools or enterprise software. It’s typically used for deeper integration with operating systems or internal corporate services.
Technical: The extension uses Chrome's Native Messaging API to interact with a native application (likely part of Microsoft's authentication infrastructure). If compromised, this could allow the extension to access sensitive data from local processes or execute arbitrary commands on the host system.
Your Data
The extension communicates with Microsoft’s Office domain and potentially other services related to authentication. It may send information such as session tokens, user identity data, or page context for sign-in purposes.
Technical Details
Code Findings
The extension connects to a program running outside the browser on your computer. This is necessary for integrating with Microsoft’s enterprise authentication system but introduces an elevated risk if that native app is compromised.
Technical: Uses Chrome's Native Messaging API, which allows communication between the extension and a locally installed application (e.g., a helper tool or service). If this process is not properly secured, it can be exploited to gain access to local data or execute unauthorized actions on the device.
💡 Common in enterprise extensions that need tight integration with OS-level authentication systems like Microsoft Entra ID. Native messaging enables secure communication between browser and system components.
The extension shares information across different websites, which is standard for SSO functionality but requires careful handling to prevent data leakage or hijacking of sessions.
Technical: Uses the window.postMessage API to send messages between frames or windows. This allows communication with external domains like https://*/*, potentially exposing session state if not handled securely by content scripts or background workers.
💡 Standard practice in SSO extensions for coordinating authentication flows across multiple sites without relying on shared cookies or tokens directly.
The extension injects code into every webpage you visit. While this is typical for SSO extensions to detect login prompts, it also means the extension has access to all page content.
Technical: Content scripts are injected into https://*/* due to Content Security Policy allowing script execution from 'self' and base-uri/form-action restrictions. This gives the extension visibility into user interactions on any site, including sensitive inputs or displayed data.
💡 Required for detecting login forms or authentication triggers across various domains during sign-in flows.
The Microsoft Single Sign On extension is designed to support enterprise identity management and integrates with Microsoft Entra ID. Its use of native messaging aligns with its intended purpose but introduces a potential attack surface that must be carefully monitored. Users should ensure their devices are managed by IT, especially on macOS where additional software like Company Portal is required. While the behavior appears aligned with official documentation, users who do not belong to an enterprise environment using Microsoft Entra ID may find little value in installing this extension.
