Outlook: Add custom sounds for Mail Notifications, Reactions, and Calendar Reminders

🚨 The Signal: Outlook users can now set custom notification sounds for emails, reactions, and calendar reminders. This change introduces a minor risk of social engineering via custom sound files.

The Impact

End users are affected by the ability to upload custom sound files, posing a low security risk if malicious files are introduced.

• End users: Can upload custom sound files, potentially introducing malware.
• Security teams: Need to be aware of new potential vectors for user-introduced content.
• IT administrators: May need to manage user-uploaded content if malicious files are identified.

The Action

1. Review existing endpoint detection and response (EDR) policies to ensure custom file types are scanned.
2. Educate users on the risks of downloading and using untrusted files, including sound files.
3. Monitor for unusual file uploads or modifications in user profiles related to custom sounds.

Domain: M365-Apps · Impact: low · Workload: M365 Apps