Threat Intelligence & APT BleepingComputer 3 weeks ago

Microsoft to retire Microsoft 365 Companion apps in December

CN
CyberNew Threat Research Desk
• Original Reporting: BleepingComputer
CyberNew Threat Intel Assessment
Assessed Severity: INFORMATIONAL
Impacted Surface
Client Endpoints & Operating Systems
Intelligence Sector
Threat Intelligence & APT

Analyst Takeaway

"Microsoft announced that it will retire the Calendar, People, and Files Microsoft 365 companion apps on December 16 and urged admins to remove them from managed devices in their organization. This follows Microsoft's October 2025 announcement that it will begin automatically installing them on all Windows 11 enterprise devices with the Microsoft 365 desktop client apps by the end of December..."

Recommended Defense & Mitigation

  • Threat Monitoring: Ingest published IOCs into SIEM/EDR detection rules for continuous telemetry monitoring.
  • Security Awareness: Alert staff and maintain baseline endpoint hardening across endpoints.
Curated & Verified by CyberNew Threat Intelligence Desk Standard Defense Framework (NIST / MITRE ATT&CK)

Microsoft 365

Microsoft announced that it will retire the Calendar, People, and Files Microsoft 365 companion apps on December 16 and urged admins to remove them from managed devices in their organization.

This follows Microsoft's October 2025 announcement that it will begin automatically installing them on all Windows 11 enterprise devices with the Microsoft 365 desktop client apps by the end of December 2025.

The Microsoft 365 companion apps integrate Copilot for contextual AI assistance and can help locate people within the organization, access Microsoft 365 and locally stored files, and manage one's schedule using the Microsoft 365 calendar from the Windows 11 taskbar.

According to Microsoft's support, once installed, these apps also launch automatically at startup by default to help users "quickly look up contacts, find files, and check your schedule without delay" and ensure they "show relevant results as soon as users open the app."

However, IT admins could also opt out of automatic installation via Device Configuration settings in the Apps Admin Center, and users could disable auto-launch from each app's Settings dialog by turning off the "Start app minimized when you log in" option.

Microsoft 365 companion apps (Microsoft)
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Source Verification & Original Intelligence

This threat report was reviewed by CyberNew analysts and cross-referenced with primary security disclosures from BleepingComputer.

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