Top 10 Microsoft Teams Security Threats

By on Oct 13, 2020

2020 has seen cloud adoption accelerate with Microsoft Teams as one of the fastest growing collaboration apps, McAfee customers use of Teams increased by 300% between January and April 2020. When we looked into Teams use in more detail in June, we found these statistics, on average, in our customer base:


Teams Created                                                                 367

Members added to Teams                                      6,526

Number of Teams Meetings                              106,000

3rd Party Apps added to Teams                                 185

Guest users added to Teams                                  2,906

This means that a typical enterprise has a new guest user added to their teams every few minutes – you wouldn’t allow unknown people to walk into an office, straight past security and walk around the building unescorted looking at papers sitting on people’s desks, but at the same time you want to allow in those guests you trust. For Teams, you need the same controls – allow in those guests you trust, but confirm their identity and make sure that they don’t see confidential information.

Microsoft invests huge amounts of time and money in the security of their systems, but security of the data in those systems and how they are used by the users is the responsibility of the enterprise.

The breadth of options, including inviting guest users and integration with 3rd party applications can be the Achilles heel of any collaboration technology. It takes just seconds to add an external third party into an internal discussion without realizing the potential for data loss, so sadly the risk of misconfiguration, oversharing or misuse can be large.

IT security teams need the ability to manage and control use to reduce risk of data loss or malware entering through Teams.

After working with hundreds of enterprises and over 40 million MVISION Cloud users worldwide and discussing with IT security, governance and risk teams how they address their Microsoft Teams security concerns, we have published a paper that outlines the top ten security threats and how to address them.

Microsoft Teams: Top 10 Security Threats

This collaboration potentially increases threats such as data loss and malware distribution. In this paper, McAfee discusses the top threats resulting from Teams use along with recommended actions.
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A few of the 10 Top Microsoft Teams Security Threats are below, read the paper for the full list.

  1. Microsoft Teams Guest Users: Guests can be added to see internal/sensitive content. By setting allow and/or block list domains, security can be implemented with the flexibility to allow employees to collaborate with authorized guests via Teams.
  2. Screen sharing that includes sensitive data. Screen sharing is very powerful, but can inadvertently share confidential data, especially if communication applications such as email are showing alerts on the screen.
  3. Access from Unmanaged Devices: Teams can be used on unmanaged devices, potentially resulting in data loss. The ability to set policies for unmanaged devices can safeguard Teams content.
  4. Malware Uploaded via Teams: File uploads from guests or from unmanaged devices may contain malware. IT administrators need the ability to either block all file uploads from unmanaged devices or to scan content when it is uploaded and remove it from the channel, informing IT management of any incidents.
  5. Data Loss Via Teams Chat and File Shares: File shares in Teams can lose confidential data. Data loss prevention technologies with strong sensitive content identification and sharing control capabilities should be implemented on Teams chat and file shares.
  6. Data Loss Via Other Apps: Teams App integration can mean data may go to untrusted destinations. As some of these apps may transfer data via their services, IT administrators need a system to discover third-party apps in use, review their risk profile and provide a workflow to remediate, audit, allow, block or notify users on an app’s status and revoke access as needed.

McAfee has a wealth of experience helping customers security their cloud computing systems, built around the MVISION Cloud CASB and other technologies. We can advise you about Microsoft Teams security and discuss possible threats of taking no action. Contact us to let us help you.

Teams is just one of the many applications within the Microsoft 365 suite and it is important to deploy common security controls for all cloud apps. MVISION Cloud provides security for Microsoft 365 and other cloud-based applications such as Salesforce, Box, Workday, AWS, Azure, Google Cloud Platform and customers’ own internally developed applications.


About the Author

Nigel Hawthorn

Nigel Hawthorn is based in London. He writes about data protection, privacy, user behavior and cloud security. He published a book called GDPR: An Action Guide for IT and talks regularly at industry events in front of senior decision-makers, IT teams and governance, risk and compliance. As well as securing cloud computing, he has experience ...

Read more posts from Nigel Hawthorn

Categories: Cloud Security

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