Teams Under Siege: Uncovering Microsoft’s Cyber Quirks 

In the modern digital landscape, enterprises utilize communication platforms to facilitate smooth interactions; however, these conveniences also open up numerous avenues that can be exploited by malicious actors. This blog, part two of the Business Communication Risks series, highlights how seemingly benign platforms can become pathways for attackers targeting individuals and infiltrating organizations. Businesses must recognize these risks, take proactive steps, and fortify cybersecurity defenses to safeguard sensitive information and operational continuity amidst evolving threats.


Microsoft Teams offers a cohesive workspace for teams to collaborate, communicate, share files, and work on projects in real time. It’s tailored to enhance communication and teamwork within various types of organizations, spanning from small businesses and enterprises to educational institutions and non-profits. Its popularity has grown significantly as organizations seek efficient ways to collaborate remotely and maintain seamless communication among team members, especially in the context of increased remote work and virtual collaboration. Microsoft Teams is currently utilized by around 91% of Fortune 100 companies making it an optimal target for cyber threat actors.

Microsoft Teams Vulnerabilities

Historically, threat actors have utilized multiple methods of exploitation techniques within Microsoft Teams to compromise sensitive corporate data. Phishing and social engineering attempts can leverage the platform, using disguises of colleagues or official communications to extract sensitive data, credentials, or malicious attachments from users. Additionally, malware dissemination can occur through shared files or links, unknowingly infecting users with harmful software. Inadequate security settings or user mistakes can lead to data leakage, exposing sensitive information to unauthorized individuals. Unvetted apps and plug-ins can introduce vulnerabilities or compromise data, as attackers may exploit weaknesses to gain access to Teams data or user accounts. Furthermore, weak passwords or compromised credentials can result in unauthorized access, allowing attackers to seize control of Teams accounts and their associated data. Moreover, regulatory non-compliance can arise from improper data handling, and the loss of control over shared data becomes a concern, particularly with shadow IT practices.

Risk in MS Teams Default Setting

Recently, a risk within the current default setting of Microsoft Teams was disclosed. This default setting enables external entities to send files to an organization’s staff, despite the application’s usual blocking of such actions. While Microsoft Teams primarily facilitates internal communication among employees, the platform’s default settings permit external users to contact company personnel. This presents an avenue for threat actors to manipulate the application for malware delivery. By exploiting this vulnerability, threat actors gain an alternative method to disseminate malware into target organizations, sidestepping the need for intricate and costly phishing campaigns. This vulnerability affects all Teams users operating under the default configuration, thereby offering significant potential for impact, and enabling threat actors to bypass conventional security controls for payload delivery.


To elevate the security of Microsoft Teams, companies should adopt a comprehensive approach:

  1. Multi-Factor Authentication (MFA) Enforcement: Enhance user authentication by mandating the use of MFA, adding an additional layer of security.
  1. Timely Software Updates: Ensure that software and applications are consistently kept up-to-date, safeguarding against known vulnerabilities.
  1. Employee Cybersecurity Training: Educate staff about potential cybersecurity threats and establish policies to restrict external sharing of sensitive information.
  1. Role-Based Access Control (RBAC) Implementation: Apply RBAC principles, adhering to the concept of least privilege, to manage access rights effectively.
  1. Anomaly Monitoring with Security Tools: Employ advanced security tools to monitor for unusual activities or breaches in real-time.
  1. Data Loss Prevention (DLP) Integration: Integrate DLP solutions with Security Information and Event Management (SIEM) systems and threat intelligence for proactive threat detection.
  1. Securing Third-Party Integrations: Ensure the security of third-party integrations, disable unused features, and maintain regular backups of critical data.
  1. Phishing Awareness Training: Equip employees with the skills to recognize and thwart phishing attempts.
  1. Patch Management: Maintain a robust system for managing software patches and updates.
  1. Incident Response Plan: Establish a well-defined incident response plan to react swiftly and effectively to security incidents.
  1. Collaboration Across IT and Security Teams: Foster collaboration between IT and security teams to promote a unified security strategy.
  1. Regular Security Audits: Conduct routine security audits to proactively identify and address vulnerabilities in the Microsoft Teams environment.


Threat actors have a range of motives for targeting Microsoft Teams, including gaining access to sensitive corporate and personal data, executing phishing attacks to extract user credentials, spreading malware through malicious links or files, exploiting software vulnerabilities for unauthorized entry, harvesting login credentials, disrupting services, launching ransomware assaults, engaging in corporate espionage, compromising third-party integrations, and tarnishing reputations by disseminating false information through compromised accounts or channels. Organizations should reduce these risks through cybersecurity training for employees, establishing security policies, enforcing role-based access controls, implementing multi-factor authentication, conducting regular audits, configuring Teams securely, preparing an incident response plan, keeping software up to date, and ensuring data encryption. Through these measures, organizations can reap the advantages of Microsoft Teams while minimizing potential cybersecurity vulnerabilities.


CRITICALSTART® offers a pioneering solution to modern organizational challenges in aligning cyber protection with risk appetite through its Cyber Operations Risk & Response™ platform, award-winning Managed Detection and Response (MDR) services, and a dedicated human-led risk and security team. By providing continuous monitoring, mitigation, maturity assessments, and comprehensive threat intelligence research, they enable businesses to proactively protect critical assets with measurable ROI. Critical Start’s comprehensive approach allows organizations to achieve the highest level of cyber risk reduction for every dollar invested, aligning with their desired levels of risk tolerance.



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