Is Microsoft Teams secure? A comprehensive review and 5 best alternatives

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In July 2023, Storm-0324, a ransomware group, exploited Microsoft Teams to distribute phishing lures. Using an open-source tool, they impersonated IT support personnel in Teams chats, deceiving employees into downloading malicious payloads.

So, is Microsoft Teams secure in 2024? 

While the platform offers data encryption and multi-factor authentication, a recent report by Skyhigh Security highlights critical gaps, including limited visibility into sensitive data movements and insufficient controls to prevent unauthorized access.

Let’s explore the platform’s security risks and vulnerabilities, along with alternative secure collaboration tools to safeguard sensitive information.

Is Microsoft Teams secure: 5 Notable security incidents

Is Microsoft Teams secure for critical organizations? The following five incidents highlight its security risks, raising concerns for enterprises handling sensitive data.

1. External communication vulnerability

In 2022, security researchers identified a critical flaw in Microsoft Teams that allowed unauthorized users outside an organization to initiate communication.

Is Microsoft Teams secure enough to prevent such violatory access? As of 2024, the tool is not completely immune to these issues. 

To mitigate the risk, disable external communication in the Teams Admin Center or implement strict allow-lists to limit interactions to trusted domains.

2. Storm-0324 ransomware

The Storm-0324 ransomware group distributes malware and facilitates ransomware access for other threat actors. They exploited Microsoft Teams as a phishing vector and delivered malicious payloads through chats.

Is Microsoft Teams secure against such sophisticated threats? 

Microsoft suspended accounts and tenants linked to fraudulent activities and also enhanced the Accept/Block experience for one-on-one chats, highlighting external users and their email addresses to identify risks.

3. Midnight blizzard attack

In 2023, the attacker used compromised credentials from previously breached accounts to impersonate technical support staff and initiate malicious conversations with corporate users.

Is Microsoft Teams secure enough to prevent nation-state actors from exploiting its vulnerabilities? 

Microsoft suspended affected accounts and reinforced authentication measures. You can verify external entities via tags and review sign-in activity to mark suspicious sign-in attempts.

4. Cross Site Scripting (XSS) vulnerabilities

With XSS, attackers can inject malicious scripts, execute unauthorized actions, and impersonate legitimate users.

CVE-2020-10146 was a notable XSS vulnerability identified within Microsoft Teams, allowing attackers to obtain authentication tokens and other sensitive information. So,

Is Microsoft Teams secure by default, or does it require constant vigilance to stay protected? 

To prevent XSS in your apps, avoid inserting untrusted data into your HTML input unless it has been encoded.

5. Increased phishing risks

In addition to advanced phishing strategies like spear phishing, attackers increasingly exploit collaboration tools to deliver malware.

APT29, a Russian-linked threat group, launched a phishing campaign targeting government and corporate entities using Microsoft Teams. With compromised Microsoft 365 tenants and legit domains like “onmicrosoft.com”, attackers manipulated users into engaging with malicious links.

At least 40 unique global organizations were affected, including government, and non-government organizations.

Is Microsoft Teams secure enough to defend against advanced phishing? 

Teams users must remain vigilant and implement robust phishing-resistant measures to address growing cyber threats.

4 security risks associated with Microsoft Teams

Is Microsoft Teams secure enough for enterprise collaboration? In 2022, the German DSK determined that Microsoft 365, which includes Microsoft Teams, does not comply with the GDPR. 

The following four risks emphasize the need for strict governance:

1. Grant user access

Allowing guest access in your Teams chats can expose sensitive data if not configured properly.

The McAfee 2021 Threat Predictions Report highlights the rapid adoption of collaboration tools like Microsoft Teams, noting that organizations added approximately 3,000 guest accounts between January and April 2020.

The surge in guest accounts emphasizes the need for robust governance to prevent unauthorized access. Misconfigured permissions can inadvertently expose sensitive files.

2. Phishing and malware distribution

In 2023, Kaspersky experts noted an increase in phishing spread via messaging platforms and blocked over 60,000 attempts to redirect users via phishing and scam links on Telegram.

Recent cases highlight Black Basta, a notorious ransomware group using Microsoft Teams and QR codes to trick users into granting unauthorized access to their accounts and systems.

One way to mitigate cyber risks is CASB solutions with advanced data loss prevention capabilities. These solutions can detect and block malicious activities in real time.

3. Data leakage through misconfiguration

In 2024, misconfigurations accounted for a substantial portion of data breaches, with 1% of incidents in December 2023 attributed to such errors. 

These mistakes involve improperly set permissions, unsecured databases, and weak access controls that expose sensitive data.

Microsoft's AI research team inadvertently exposed 38 terabytes of private data while sharing open-source training models on their GitHub repository.

The research team had misconfigured the Azure Shared Access Signature (SAS) token. This granted full access to the entire storage account and exposed sensitive internal data, including passwords, private keys, and over 30,000 Microsoft Teams messages.

Wiz Research Team uncovered this incident in 2023 while investigating the accidental exposure of cloud-hosted data.

4. Compliance challenges

A recent TechTarget ESG study revealed that organizations formally sanction multiple communication platforms, making it challenging to implement consistent security and compliance policies.

While Teams comply with regulatory standards like HIPAA and ISO 27001, its distributed file storage across channels, chats, and tools like SharePoint and OneDrive makes it challenging to locate and manage sensitive data effectively.

Additionally, Teams’ dynamic messaging nature allows users to share sensitive or restricted content and then delete the messages to erase evidence. This impacts industries with strict compliance requirements, such as healthcare, finance, and government sectors.