Microsoft has issued comprehensive security guidance for Microsoft Teams amid a rising threat landscape.
The advisory details how threat actors can abuse Teams’ core features—including chat, meetings, voice and video calls, screen sharing, and app integrations—to compromise corporate networks, establish persistence, and exfiltrate sensitive data.
Outlining specific countermeasures, the blog post explains steps organizations should take to protect themselves from the attacks targeting the collaboration platform.
What makes this announcement particularly significant is not simply its content but its source. Typically, warnings about vulnerabilities in widely deployed collaboration platforms emerge from third-party security researchers or incident response firms.
Yet seeing Microsoft issue this guidance reflects the fact that the Teams platform is facing increased threat activity that must be addressed.
The Security Steps Microsoft Recommends
Microsoft highlighted several critical access vectors that organizations must address amid this new threat landscape.
To help users understand how attacks manifest, it issued guidance that maps the complete attack lifecycle as it unfolds within the Teams environment.
This begins with reconnaissance activities conducted before threat actors ever make direct contact with targets.
Adversaries can enumerate users, teams, channels, tenant configurations, and cross-tenant collaboration policies by using Microsoft Graph APIs and open-source intelligence tools.
When organizations maintain overly permissive privacy settings, external access configurations, or federation restrictions, they inadvertently expose valuable information about their internal structure, communication patterns, and security posture.
The advisory then outlines how attackers leverage this reconnaissance to craft highly targeted social engineering campaigns.
Increasingly, threat actors are establishing legitimate Entra ID tenants, registering custom domains, and developing branded assets that convincingly impersonate internal IT support or help desk operations.
These sophisticated pretexting operations allow criminals to schedule private Teams meetings, use voice and video capabilities, and leverage screen-sharing features to build credibility with potential victims—tactics that significantly increase the success rate of credential theft or malware deployment attempts.
Social engineering via Teams chat and meetings has also become a primary initial access method, with attackers distributing remote monitoring and management tools or directing users to compromised websites hosting drive-by downloads.
The guidance notes how adversaries also exploit adaptive authentication workflows and multi-factor authentication fatigue, enroll alternate authentication factors under their control, or use device code phishing to steal session tokens and maintain persistent access.
Once established within an environment, attackers abuse Teams’ legitimate functionality to achieve their objectives.
Microsoft explains how compromised credentials enable threat actors to impersonate users through Teams APIs, request OAuth tokens, and systematically enumerate applications, files, and conversations.
Persistence mechanisms range from modifying startup configurations to adding unauthorized guest users to Teams accounts.
