Microsoft 365

08 December 2021

Microsoft Teams: 5 key points to improve data protection

microsoft teams data protection

In a context of crisis and widespread remote working; The use of collaborative tools such as Teams was essential to maintain the fluidity of remote exchanges between employees.

The total control of the functioning, the sharing, configurations that the tool offers is a particularly sensitive subject, especially for Microsoft 365 data protection.

Microsoft Teams,

collaborative tool that has transformed the way of work 

Microsoft Teams application has seen a surge in usage since March 2020. It is growing from 44 million users to 145 million in less than a year. (1) 

 Teams holds a powerful feature set that has been growing steadily since its inception in 2017 (instant messaging and calling, video conferencing, task scheduling, project management, and file sharing and storage) . With this collaborative tool, users have a great autonomy of use. This is what makes it a complex tool, both to manage from an administrative point of view but also for the users who are confused in their uses.  

According to an IFOP survey, 25% of employees don’t use some IT tools (shared documents, remote connection, collaborative tools, etc.) for fear of security or confidentiality problems

The autonomy of users, the collaborative nature of the tool and the emergence of new functionalities pose real constraints for IT teams. Indeed, They are faced with a large volume of data to supervise. They must adapt their security policy so as not to block too much or give too many rights to users in order to reduce risks. And let’s not forget that the massive adoption of Teams was recently done in a context of crisis and emergency. Plus, the cyber context puts additional pressure in the detection of intrusions and threats. 

So how do you ensure better data governance and protection for Microsoft Teams ? 

Understand and control the risks related to Microsoft Teams 

A collaborative and connected tool 

With Teams, employees have become hyperconnected thanks to its application that acts as a personal messaging application (Messenger, WhatsApp…). Exchanges between teams have become very accessible: from anywhere (at home, on vacation or at the office), from any device (e.g. tablet, mobile, laptop) or at any time. This ultra-connectivity creates risks for the company’s data and requires IT teams to be even more vigilant.  Who does what ? And can do what ? Who shares what ? Data sharing evolves instantaneously and can give way to malicious intent or compromission (e.g. identity theft, access from a suspicious country or connection from a new device). 

Teams/SharePoint: how does it work? 

Each user can be a member of more than 1000 different Teams. (Microsoft)  

A Teams team may include 25000 members (Microsoft)  

Teams and SharePoint are two tools that complement each other. 

Teams files are stored in SharePoint: 

Microsoft Teams SharePoint scheme
Source : Microsoft

Each time a Teams « crew » is created, at the same time SharePoint will create a file library to manage and store the documents of the space (e.g., “files” tab in Teams). The SharePoint library is directly accessible through the Teams channel.

SharePoint backs up files deleted from Teams: it is not possible to recover a deleted file via Teams but via the SharePoint trash associated with the Team for a duration of 30 days.

  • The SharePoint Online administration console defines the default configurations:
    • External sharing  
    • Link types, link expiry times  
    • Permission groups   
  • and completes those of Teams:

Teams has three levels of access:

    • The owner who has full control  
    • Members who can edit
    • Visitors who just have the right to read

  It is possible to refine these access rights via SharePoint online. 

The risks of sharing: external, malicious, illegitimate 

The risk of fraud on Information System through access, configuration or sharing can be significant for a company. The risks and threats are numerous.  

  • Compromised account and data disclosure:

MALICIOUS/ ILLEGITIMATE SHARING: Data shared with one or more correspondents can be disclosed against the user’s will if one of the accounts is compromised. The occurrence of the risk can be complex to detect as it requires the user to be aware of it. 

  • Configuration errors and too much access:

ANONYMOUS / ILLEGITIMATE SHARING: The increase of sharing methods means that a configuration error is always possible. This error can come from the user or the administrator. (Ex: A collaborator shares a sensitive file via an anonymous link to a colleague. If the latter decides to transmit the link to another person or to an external account, an information leak can quickly occur…) 

  • Management of shares over the time:

EXTERNAL / OUTDADED SHARING: It is important to have control over your rights so that they don’t become obsolete at a given moment. To do this, it is important to check if the people who have access to the data are still legitimate to access it (e.g.: service provider on an old project).  

In order to avoid human errors and risks of data leakage, it is important to permanently control accesses, rights, shares and configurations on Teams.


Improve control of rights on Teams 

Ensure that data at any given moment in time is accessed and shared by and with the right people. Inside and outside the company:   

  • An administrator can define security configurations for users: Users cannot go against an administrator and be more permissive than the established rules. (e.g., not being able to invite guests into a Teams channel) 
  • Follow the evolution of rights: They can become obsolete or result from a handling error. For example, if a person is no longer authorized to access a company file (former employee, internal transfer, external consultant) or if an employee has given too many rights to a file when sharing it.  
  • Separate personal and professional devices in order to manage and control the installation and synchronization of applications, especially on mobile phones : You must be vigilant about the level of rights granted when synchronizing a new app, which, if compromised, can be the source of an intrusion or leak.  
  • Manage compliance for sensitive data: Confidential documents, strategic groups and teams… Make sure that only legitimate people have access to this data.  
  • Verify what guests have access to in Teams: Guests have access to all files shared in Teams, yet there are no procedural restrictions to determine their access privileges. 

What sharing strategy to adopt on Teams? 

  • Optimize your share visibility: Microsoft offers a new drop-down menu. It allows better visibility and easier access to additional sharing options such as access settings management, link copy, email and Microsoft Teams conversation.

Update Microsoft
Source : onmsft

  • Avoid share hijacking via SharePoint: Internal collaborators who are not part of a Teams group can still access files which are in the group if someone shares them via SharePoint.   
  • Avoid illegitimate sharing: In Teams groups, many files are shared to members and guests. It is important to check if there is a risk of illegitimate sharing with guests (e.g. providers, suppliers) having access to confidential company files. 

Protecting sensitive data on Teams 

Concerning sensitive data, it is important to identify and map them: where are they located? which people have legitimate access to them? who can access them? in order to define the levers to be put in place: 

  • Declare external users via Azure AD: From Azure AD, administrators can choose which external users have the same security rules as an internal collaborator. (e.g. MFA, connection time)  
  • Create collaborative resources management by Teams’s owners: It is important to empower each Teams group owner to supervise access to sensitive or even confidential resources. Answer the question “Who has access to what?” in order to determine to whom they give access, rights and shares over time.  
  • Classify sensitive data via MIP: MIP allows to classify sensitive data within a Teams shared folder. It even allows to encrypt some documents and folders called ‘highly confidential’ to avoid sharing or illegitimate access. 
  • Manage sensitive groups : Teams allows you to create a large number of conversations and groups. To keep track of sharing, it is important to distinguish sensitive groups on Teams as well as members and guests before sharing confidential files. (Ex: R&D groups deal with more confidential files).    
  • Create private channels: Teams allows you to restrict access to a specific channel. This action allows an owner or team member to secure some information to a group of individuals. By creating a private channel, the user will have to select the people who can access it. It is then possible to restrict access to so-called “sensitive” information. (to external people or people who are not authorized to access the information).
    Also coming soon, Teams Connect (or shared channels) will allow to give access to a channel without any visibility on the rest of the team.

As a reminder, it is possible to apply rights and sharing restrictions on a specific folder or directory via SharePoint online. 

Ensure the follow-up of sharing in Teams over time 

It is important to control the sharing in Teams to avoid malicious, illegitimate or anonymous sharing.   

  • Be able to identify and correct too high rights:  

                    • Do not give too high rights to some members : Establish a scale of rights according to the member, in order to avoid human errors. (e.g. the principle of least privilege which allows to restrict the access rights of a specific user, so that he has access only to the files necessary to perform his work). 

                    • Avoid rights escalation: Each member having received rights on a file. Then they can share it with other non-legitimate members. It is therefore important to define who should be given the rights to confidential data. 

  • Inactivate external sharing: It is possible for each administrator to inactivate external sharing of a SharePoint/OneDrive file by blocking domains not belonging to his organization. It is impossible to add sensitive files via Teams including guests.  
  • Keep an eye on the evolution of the collaborative tool: Teams is a collaborative tool that is constantly evolving and offering new sharing features for users. It is important to follow its updates to effectively protect and optimize the protection of its sensitive data. Relying on specialized expertise or solutions allows you to effectively manage these changes for your IS.  
  • Guarantee the correctness of rights by reviewing rights (recertification of shares): It is important to regularly review the rights granted to members and guests to rectify obsolete and illegitimate rights. (e.g.: people who no longer need access to documents, former collaborators) and particularly over time.

Raising awareness and involving the user in data protection  

Raise awareness and empower employees 

“60% of cyber-attacks can be attributed to inappropriate human behavior” – Accenture   

It is important for IT and Digital Workplace managers to raise awareness and involve employees in the dangers of data leakage. Employees must become more familiar with the tool to avoid any handling errors.  

To raise cyber awareness among employees, companies can implement various actions: 

  • Workshops: This format of meeting allows to work in a collaborative way with the collaborators. In order to sensitize them to the use of collaborative tools like the creation of Teams or functional channels on Teams.  
  • Training: The purpose of training employees is to make them aware of several functionalities of the tools. The possible uses to be transcribed in their daily life and in the uses of their company. (e.g., in the context of remote work where the use of Teams has been very important)  
  • Recertification campaigns: Setting up campaigns with employees allows to remind them, at the desired frequency, to maintain the correct rights on Teams and to identify any configuration error.   
  • Internal communication: Companies can implement various marketing actions such as emailing to remind the issues of data protection. (in the use of Teams, SharePoint or OneDrive). 

These various awareness-raising actions will also allow them to become more involved in the protection of their data, and to make them more responsible by:  

               → A better use of their collaborative tools  

               → Autonomous management of their access, rights and sharing   

               → An up-to-date review of rights over time 

Provide visibility and confidence in the use of collaborative tools 

Giving users visibility into the use of their data reassures them, involves them and encourages them to use the tools wisely.  

According to a recent IFOP study, more than 8 out of 10 employees want to be involved in the security of their company’s data. (IFOP). And 81% of the employees surveyed would like to have a dashboard to track who is doing what? Who can do what? Who has access to what?  

Indeed, a better visibility of users on their accesses, rights, sharing has several benefits: 

  • Alerting security teams: Users can identify malicious behavior or compromises that may indicate the start of an intrusion and inform the SOC or ISS teams: 
    • A new illegitimate connection
    • Access from an unidentified device
    • Malicious or anonymous sharing on Teams 
  • Correct their handling/configuration errors: Users can directly correct anomalies related to their account: 
    • A right too important
    • Illegitimate access to sensitive data
    • Obsolete shares   

Awareness and visibility allow users to gain efficiency in the use of Teams, SharePoint and OneDrive and to avoid heavy consequences of a configuration error related to the normal activity of a user.    

On Teams, owners must also have a perfect vision of the composition of their Teams and channels to quickly correct configuration errors: 

    • Legitimacy of members and guests in Teams and Channels
    • SharePoint sensitive files shared in their Teams 
  • Help IT teams during a doubt removal: Users are more likely to know if it is a false positive because it is their data. IT teams need to communicate easily and directly to users to clear a suspicion (e.g., work location has changed, Teams application is connected to a new phone). This saves time for IT teams in the volume of incidents to be handled. 

Doing so via a simple and user-friendly tool would allow the user to be more involved in the sound management of his data, and that of the company, as well as in the appropriation of the various risks of data leakage. 

Protect your data on Microsoft Teams with IDECSI

Collaboration and cybersecurity are the two main challenges of data protection for companies. Involving users seems to be a must today, given their autonomy in the use of collaborative tools, and the constant evolution of an increasingly powerful tool like Teams.  

IDECSI solution “MyDataSecurity» allows each employee to have maximum visibility thanks to a personalized dashboard grouping rights, accesses and shares. The user can identify at a glance its configuration errors and anomalous behaviors and then report them to the IT teams or remedy them directly. And thanks to an expert back office, IT teams can supervise operations and gain in efficiency (SOC optimization, analysis).  IDECSI relies on preconfigured threat models and real-time alerting of the most virulent threats. 

With IDECSI, you benefit from a SaaS platform for monitoring, detection, auditing and remediation of Microsoft 365 and on-premise data, and position each user as a contributor to the security of their company. 

1. Microsoft Teams compte désormais 145 millions d’utilisateurs actifs quotidiens (
2. Accenture, « State of Cybersecurity Report 2020
3. IFOP survey

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