Microsoft Teams users receive bizzare ‘FCM Messages’ notifications, here's what happened

Several Microsoft Teams users reported “FCM Messages” notifications that didn't do anything but spammed them for a few hours.

Microsoft Teams. (Microsoft )

Microsoft Teams users were kind of bombarded with test notifications. Users reported receiving these test notifications for a couple of hours with one of them having received a total of 14 notifications.

The Microsoft Teams notification reads, “FCM Messages” with “Test Notification!!!!” at the bottom. Some users pointed out notifications saying “Testing notification from Microsoft to investigate the problem.” In some cases the icon for the notification was not the Microsoft Teams one but a solid circle. Tapping on the notification doesn't do anything and the alert just disappears after that.

Microsoft Teams FCM Messages. (Twitter/Screenshot)

Microsoft Teams FCM Messages. (Twitter/Screenshot)

The test notifications obviously shocked Microsoft Teams users and led them to thinking that there was some bug in the app. Microsoft was also informed about the issue and said that they are investigating it. The company later updated that this was affecting only Android users and advised users to dismiss the notifications and not interact with them. Microsoft then identified the issue and fixed it. Post this Microsoft Teams users did not receive any such notifications.

We've isolated the source of the issue and applied a mitigation. We've confirmed that no further unexpected notifications are being sent to users' Android devices. Additional details can be found in the admin center under TM221041.

— Microsoft 365 Status (@MSFT365Status) August 27, 2020

While the test notifications posed no threat, it could be related to a vulnerability discovered in FCM which stands for Firebase Cloud Messaging. This is a Google-owned service that apps use to send notifications to smartphones. FCM had a bug that allowed hackers to exploit its keys that are stored in APK files. Google patched the vulnerability, and these notifications could have been sent to test it out.

There have been similar incidents in the past where Paytm users in India received pushed notifications that said “hey, ghvkjfjg.” OnePlus 7 Pro users also spam notifications which the company said was due to a failed internal test.