September 22, 2025
Let’s start with the good news. Microsoft has spent, and will continue to spend, billions of dollars on cybersecurity. And Microsoft Teams has revolutionized workplace collaboration, allowing people to collaborate in real-time from anywhere on a feature-rich and user-friendly platform.
However, Teams’ integrations with SharePoint, OneDrive, and Entra ID can lead to a security challenge that many organizations overlook. When these powerful tools work together seamlessly, a misconfiguration in one area can quickly cascade across your entire Microsoft ecosystem — turning your biggest productivity advantage into your most vulnerable point of exposure. In this blog, we’ll talk about best practices to help you make the most of the Teams platform while keeping your data protected.
Microsoft Teams Security Issues To Be Aware Of
Without best practices in place, Teams users can create public-facing teams, share files externally, and allow guest access without any oversight. Even employees with the best possible intentions can do real harm.
Even if your team is incredibly security-conscious, Teams itself isn't immune to security flaws — no cloud platform is. Case in point: Back in 2020, a Teams vulnerability was discovered that allowed attackers to hijack accounts through malicious GIFs.
Microsoft Teams Security Features
According to Microsoft’s shared responsibility model, while Microsoft is responsible for securing and maintaining its tools, end users are responsible for protecting their data, endpoints, accounts, and access.
Teams comes loaded with the following enterprise-grade protections that can keep your organization safe:
Single Sign-On, MFA, and Conditional Access Controls
Single sign-on means your users can jump into Teams with their regular corporate credentials — no additional passwords needed. And when you layer on multifactor authentication, you're adding that crucial second checkpoint that can stop 99.9% of all account hacks.
The real power, though, lies in conditional access policies, where you get granular control over who can access what, when, and from where. Want to block access from certain countries? Done. Need to ensure only compliant devices can join meetings? You've got it. It's like having a smart security system that adapts based on risk levels.
Comprehensive Encryption in Transit and at Rest
Microsoft takes encryption seriously with Teams. Every message, file, and video call gets TLS (Transport Layer Security) encryption while traveling between devices and Microsoft's data centers. But the protection doesn't stop there. Once data reaches Microsoft's cloud infrastructure, it's secured using enterprise-grade encryption at rest.
For data stored in SharePoint and OneDrive (which includes all Teams files), Microsoft uses AES 256-bit encryption with unique per-file keys. Each file is split into encrypted chunks that are distributed across multiple Azure storage accounts, with the encryption keys themselves being encrypted and stored separately. This multi-layered approach means that even if someone gained access to one component, they couldn't reconstruct your data without access to all the other encrypted pieces.
Compliance Center Integration and Data Loss Prevention
Teams hooks directly into Microsoft 365's Compliance Center, making it easy to manage all your governance policies in one place. Data loss prevention policies can act like smart guardrails to prevent sensitive information from getting shared.
Advanced Threat Protection and Safe Links
Teams doesn't just rely on perimeter security. Through Microsoft Defender integration, every file and link gets scanned in real-time. Share a document with malware? It gets caught. Click on a suspicious link? Teams either blocks it entirely or routes you to a safe warning page first.
This kind of protection is important because threats often come from the inside, whether that's a compromised account or an employee who accidentally clicks something they shouldn't.
Audit Logs and Usage Reporting
Teams’ audit logging capabilities give you forensic-level visibility into who logged in when, what files were accessed, and which changes were made. This information is invaluable when investigating an incident or demonstrating compliance during an audit.
Usage reports can also help you spot patterns that might indicate security issues, like unusual external sharing activity or accounts accessing data outside normal business hours. Sometimes the best security insights come from simply understanding how your platform is actually being used.
Microsoft Teams Security Best Practices
If you handle sensitive data, securing your accounts and data within Microsoft Teams is non-negotiable. Fortunately, a few smart configurations can dramatically improve your security posture.
Switch to Allowlist-Only External Domain Communication
Microsoft's default "talk to everyone" approach might seem collaborative, but it's a reconnaissance goldmine for attackers. We recommend using an allowlist model and adding specific domains when your teams need to collaborate with external partners. Yes, it's a bit more administrative overhead, but doing it this way dramatically reduces your attack surface from random phishing attempts and social engineering.
Restrict Team Creation Rights & Address Ownerless Groups
When everyone can create teams whenever inspiration strikes, you end up with a sprawling mess of overlapping channels, duplicate conversations, and orphaned data. But the problem doesn't stop there. Groups can also become "ownerless" when the original creator leaves the organization, creating security risks and governance headaches.
Having an approval workflow isn't about stifling collaboration. It's about making sure that new teams serve a real purpose and follow your naming conventions and governance standards. Equally important is implementing Microsoft 365's ownerless groups policy, which automatically identifies teams without owners and prompts active members to take ownership.
Here’s what we’d recommend:
- Implement approval workflows for new team creation
- Set up the ownerless groups policy to automatically address ownership gaps
- Establish clear naming conventions and governance standards
- Regularly audit existing teams for relevance and ownership
By combining creation controls with proactive ownership management, you'll maintain a cleaner, more secure Teams environment that actually serves your organization's collaborative needs.
Activate Safe Links and Safe Attachments Protection
Safe Links scans every link in real time. When combined with attachment scanning, these features catch a surprising amount of malware and phishing attempts before they can do damage. The best part? They work automatically in the background.
Disable Third-Party File Storage Integrations
Teams works beautifully with SharePoint and OneDrive, but it also opens the door to every file-sharing service under the sun. When users start dropping Dropbox links, Google Drive shares, or random cloud storage URLs into Teams channels, your data governance goes out the window. Blocking third-party storage integrations keeps your sensitive files within your controlled ecosystem, where your security policies actually matter.
Enable Lobby Controls for All Meeting Types
Meeting security often gets overlooked until it's too late. When anonymous users can hop directly into your meetings without any oversight, you're essentially leaving your conference room doors wide open. Requiring explicit approval for external participants might add a few seconds to meeting starts, but it prevents those awkward moments where competitors, trolls, or worse end up in your strategy sessions.
But lobby controls are just the first line of defense. You should also configure participant restrictions to limit what attendees can do once they're in your meetings:
- Restrict who can present
- Disable the ability for participants to give or request control of shared screens, especially for external participants
- Prevent external users from taking control during presentations or sharing content without explicit approval
These granular controls ensure that even if someone makes it past your lobby, they can't disrupt your meeting or gain access to sensitive information through screen sharing or presentation privileges.
Create Private Teams for Sensitive Project Work
Not every conversation needs to happen in front of the entire organization. Private teams give you surgical control over who accesses specific information, reducing the blast radius if something does go wrong.
Private channels can also give users the ability to create secure spaces within the broader collaboration environment — perfect for executive discussions or project work that needs tighter access controls.
Implement App Permission Policies for Third-Party Applications
By default, Microsoft lets users install whatever third-party apps catch their fancy. Unfortunately, each one represents a potential gateway to your data. We recommend starting with everything blocked and approving apps on a case-by-case basis.
Configure Data Retention Policies To Prevent Permanent Deletion
If you take nothing else away from this blog, update Teams’ default deletion settings. When employees can permanently wipe messages and files that are less than a year old, some of your most valuable information is at risk.
Additional Help Securing Your Microsoft Environment
According to a Gartner analyst, 80% of cloud breaches are due to customer misconfiguration, mismanaged credentials, or insider theft, not cloud provider vulnerabilities. Teams and other Microsoft security incidents tend to happen not because Microsoft’s protection failed, but because organizations never configured their tools properly. But to be fair, securing Microsoft requires advanced skills.
As a Microsoft Solutions Partner, our team specializes in secure configuration and providing a simpler end-user experience. We’ve developed a new service to help organizations get right-sized IT support for their Microsoft tools and data. It’s a great fit for SMBs that want additional help for the tools they use most at an affordable price point. Click the link below to see what’s included!
