Solarwinds app installed itself into our organization's Teams client without permission.

This sounds troubling have you logged it with support?

Yes there response was "SolarWinds Service Desk does not have the capability to deploy this Teams Plugin on your Organization. As per documentation it is required that the Teams plugin will be installed initiated by the user under the Teams Apps Lists".

The only explanation I can think of that barely makes sense is the SSO integration somehow triggered a login to the app, but that's a reach.

There are some oddities with the ms app stores that can allow users to install apps on their own. I would see if it shows up on your teams app list if you search on SolarWinds.

This is indeed an unusual situation. You're right, it's highly unlikely for the SolarWinds Teams app to install itself without any explicit action from either the users or the admin side. Here are some additional points and potential causes to investigate:

Possible Explanations:

• Accidental User Installation: While you say it's unlikely, it's still possible that some users might have inadvertently installed the app from the Teams app store. You could check with a few users to see if they recall doing so.
• Third-Party App Integration: Is there any other third-party application integrated with your Teams environment that might have triggered the installation? Some apps have the ability to add other apps as part of their functionality.
• Teams Policy Update: Although you've checked the policies, it's worth double-checking if any recent updates to Teams policies or settings might have inadvertently enabled app auto-installation.
• Microsoft Side Issue: While SolarWinds support says it's not possible, there might be a rare bug or issue on the Microsoft Teams side that caused this.

Further Troubleshooting Steps:

1. Check Teams Admin Center: Go to the Teams Admin Center and look for any app-related settings or policies that might be relevant.
2. Review Audit Logs: If possible, check the audit logs in the Teams Admin Center or Microsoft 365 admin center to see if there's any record of the app installation.
3. Reach Out to Microsoft Support: If you're unable to find any explanation within your environment, contact Microsoft support and provide them with details about the issue. They might have insights into any known bugs or issues that could cause this behavior.
4. Consider Security Implications: If you're still unable to determine the cause, consider the potential security implications. Even if the app is legitimate, unexpected installations can indicate a potential vulnerability in your Teams environment.

It's commendable that you're taking a proactive approach to investigate this issue. Unexpected app installations can sometimes be a sign of unauthorized access or malicious activity.

Make sure to document your findings and communicate them to your IT security team or management, even if the cause turns out to be benign.

I am just dealing with missing buttons on Web Help Desk after applying Hot Fix!   Good Luck; I am most certain it is benign!

Calling it now, someone hit an install button somewhere