Information
Anonymous users are users whose identity can't be verified. They may be logged in to an organization without a mutual trust relationship or they may not have an account (guest or user). Anonymous participants appear with "(Unverified)" appended to their name in meetings.
These users could include:
- Users who aren't logged in to Teams with a work or school account.
- Users from non-trusted organizations (as configured in external access) and from organizations that you trust but which don't trust your organization. When defining trusted organizations for external meetings and chat, ensure both organizations allow each other's domains. Meeting organizers and participants should have user policies that allow external access. These settings prevent attendees from being considered anonymous due to external access settings. For details, see IT Admins - Manage external meetings and chat with people and organizations using Microsoft identities
The recommended state is Anonymous users can join a meeting unverified set to Off
For meetings that could contain sensitive information, it is best to allow the meeting organizer to vet anyone not directly sent an invite before admitting them to the meeting. This will also prevent the anonymous user from using the meeting link to have meetings at unscheduled times.
Note: Those companies that don't normally operate at a Level 2 environment, but do deal with sensitive information, may want to consider this policy setting.
Solution
To remediate using the UI:
- Navigate to Microsoft Teams admin center
https://admin.teams.microsoft.com
.
- Click to expand Meetings select Meeting policies
- Click Global (Org-wide default)
- Under meeting join & lobby set Anonymous users can join a meeting unverified to Off
To remediate using PowerShell:
- Connect to Teams PowerShell using Connect-MicrosoftTeams
- Run the following command to set the recommended state:
Set-CsTeamsMeetingPolicy -Identity Global -AllowAnonymousUsersToJoinMeeting $false
Impact:
Individuals who were not sent or forwarded a meeting invite will not be able to join the meeting automatically.