Threat Actors Use Microsoft Teams to Mask Malware Traffic
The hacking group known as DragonForce has exploited Microsoft Teams to bypass corporate security filters and establish command-and-control (C2) communication. By routing malicious traffic through legitimate Microsoft infrastructure, attackers disguise data exfiltration as standard business communication, making it significantly harder for traditional network monitoring tools to flag unauthorized activity.
How DragonForce Uses Microsoft Teams for C2
Security researchers at Cisco Talos identified that DragonForce leverages the platform’s legitimate API endpoints to facilitate C2 operations. By utilizing the platform’s trusted domain, the malware avoids triggering alerts that typically occur when internal systems attempt to connect to unknown or malicious external IP addresses.
The process involves the deployment of custom malware that interacts with Microsoft Teams’ webhooks. Because the traffic originates from a domain that is inherently trusted by most enterprise firewalls, security teams often overlook the connection. This technique allows attackers to maintain persistent access to a compromised network, exfiltrate sensitive files, and receive instructions while remaining hidden in plain sight.
Why Trusted Infrastructure Complicates Detection
The reliance on software-as-a-service (SaaS) platforms creates a blind spot for many organizations. According to CrowdStrike, adversaries increasingly favor “living-off-the-land” techniques, where they use pre-installed or trusted software to conduct malicious operations.
Unlike traditional malware that connects to a suspicious server, DragonForce’s use of Microsoft Teams exploits the inherent trust organizations place in the Microsoft 365 ecosystem. This creates a significant challenge for Security Operations Centers (SOCs). Standard URL filtering and domain reputation services often whitelist Microsoft domains, meaning the traffic is rarely inspected for malicious payloads or abnormal behavioral patterns.
Comparison of Threat Vectors
| Vector | Detection Difficulty | Mechanism |
|---|---|---|
| Traditional C2 | Moderate | Connects to known malicious IPs/domains. |
| SaaS-Based C2 | High | Uses trusted APIs (e.g., Microsoft Teams, Slack). |
Protecting Enterprise Environments
To mitigate the risks associated with SaaS-based C2 activity, security experts recommend moving beyond simple domain-based blocking. The Cybersecurity and Infrastructure Security Agency (CISA) suggests adopting a Zero Trust architecture, which mandates continuous verification of all traffic, regardless of its origin.
Key defensive strategies include:
- API Monitoring: Implement solutions that inspect API traffic for unusual patterns, such as excessive data transfers or unauthorized webhook creation.
- Endpoint Detection and Response (EDR): Focus on identifying the initial execution of the malware on the local machine rather than relying solely on network-level blocks.
- Least Privilege Access: Limit the ability of applications and users to create or modify webhooks within the Microsoft Teams environment.
As threat actors continue to shift their tactics toward leveraging trusted cloud services, the focus for cybersecurity teams must evolve from simple perimeter defense to granular behavioral analysis of application-layer traffic.