Microsoft Teams has become a central hub for teamwork, communication and collaboration – but with that popularity comes increased attention from cyber criminals. Recent security intelligence shows that attackers are now exploiting legitimate Teams functionality to impersonate Microsoft services, trick users, and steal login credentials. What makes this threat especially dangerous is that these attacks do not rely on software vulnerabilities, they are simply exploiting trust.
According to Microsoft‑linked threat reporting, attackers are abusing built‑in Teams features such as external messaging, guest invitations, and even legitimate Microsoft notification channels to deliver fake alerts, impersonate Microsoft security messages and lure users into credential‑stealing traps.
Below is a breakdown of how these attacks work, and how CSG’s multi‑layered security solutions can protect your organisation against this Microsoft Teams update, where hackers are exploiting Teams to steal credentials by mimicking Microsoft.
How are the hackers exploiting Teams?
1. Abuse of the “Invite a Guest” feature
Cyber criminals create new Teams groups with fake billing alerts or urgent Microsoft‑branded warnings, such as false “Auto‑Pay Notices” or account security alerts. They then use Teams’ legitimate Invite a Guest feature to send trustworthy‑looking invitations from real Microsoft‑owned email domains.
Because these emails come directly from Microsoft infrastructure, they pass SPF, DKIM and DMARC checks, making them highly convincing.
2. Impersonation of Microsoft services
Attackers craft team names and messages mimicking real Microsoft communications, for example:
- “Your password expires today”
- “Unusual sign‑in detected”
- “Billing issue – action required”
The formatting, language and urgency match true Microsoft notifications, causing users to respond quickly without verifying legitimacy.
3. Social engineering without malicious links
Unlike traditional phishing attacks, these Teams‑based scams often avoid risky links altogether. Instead, they:
- Provide a fake support phone number
- Engage victims in real‑time
- Extract login credentials verbally
This tactic [known as vishing] makes detection significantly harder.
4. Credential stealing & account takeover
Once attackers gain your Microsoft 365 credentials, they can:
- Access Teams, SharePoint and Outlook
- Steal data
- Impersonate users internally
- Spread further phishing campaigns across your organisation
Microsoft warns that attackers can remain inside compromised tenants for days by manipulating inbox rules, deleting alerts, and blending in as legitimate users.
Why is this threat growing?
Microsoft’s security research notes that collaboration tools like Teams are now high‑value targets because they rely on real‑time interaction and trusted internal communication, creating a perfect environment for social engineering. Attackers know:
- Users move faster in chat than in email
- Teams doesn’t raise the same suspicion as email phishing
- Real Microsoft systems send notifications often, making impersonation easier
With millions of organisations adopting Teams as their primary communication channel, attackers have seized the opportunity.
What’s the solution?
At CSG, we deliver a modern, multi‑layered security framework built to defend against exactly this type of threa, including identity attacks, Teams impersonation and social‑engineering‑driven credential theft.
1. Identity & access security
Our solutions integrate Microsoft Entra ID protections with:
- Conditional Access Policies
- MFA hardening
- Risk‑based access control
- Session monitoring & anomaly detection
These measures limit what attackers can do, even if they trick a user, which is Supported by Microsoft’s own recommendations for identity‑first security.
2. Teams‑specific hardening
CSG configures advanced Teams security settings including:
- Restricting or managing external access and guest invitations
- Enabling Microsoft’s brand impersonation protections
- Implementing Teams‑specific threat monitoring
This aligns with Microsoft’s latest advisories around securing Teams collaboration environments.
3. Multi‑layer endpoint & threat protection
Using Microsoft Defender solutions, we protect users against:
- Malware delivery
- Malicious attachments
- Unsafe links
- Account takeover attempts
- Persistence mechanisms used by attackers
Microsoft confirms that Teams can be abused at nearly every stage of the attack chain, making endpoint protection critical.
4. Security awareness training
CSG delivers specialised training to teach users:
- How to identify fake Teams notifications
- Warning signs [urgent billing alerts, mixed characters, phone‑only instructions]
- Safe verification practices
Microsoft’s reporting stresses that user assumptions [not software flaws] are the biggest risk.
5. Full Microsoft 365 environment hardening
Including:
- Secure configuration of SharePoint, OneDrive and Exchange
- Alerting on suspicious Teams or account activity
- Monitoring cross‑tenant behaviour
- Preventing external enumeration and reconnaissance
Hackers aren’t waiting for you to check your email, they are coming directly into Microsoft Teams, where users feel comfortable and trust the platform by default. As Microsoft’s own research shows, attackers are exploiting collaboration features, identity systems, and user behaviour to steal credentials and infiltrate organisations. [microsoft.com]
CSG’s layered security approach ensures your people your data, and your Microsoft 365 environment remain protected [no matter what new tactics attackers use].
