MeetC2 is a novel serverless command and control (C2) framework that exploits Google Calendar APIs as a covert communication channel for botnet operations. Unlike traditional C2 infrastructures that rely on dedicated servers or compromised hosts, MeetC2 leverages legitimate cloud services—in this case, Google Calendar—to send and receive commands between attackers and compromised endpoints. This approach enables attackers to bypass many network security controls that typically monitor or block suspicious outbound connections, as Google Calendar traffic is generally considered benign and is widely allowed in corporate environments. The framework operates by encoding commands within calendar events or metadata, which infected hosts periodically query and parse to execute instructions. This method provides a stealthy, resilient, and hard-to-detect communication mechanism, as it blends malicious traffic with legitimate API calls to a trusted cloud service. The serverless nature of MeetC2 means there is no need for attackers to maintain dedicated infrastructure, reducing their operational footprint and increasing the difficulty of attribution and takedown. Although no known exploits leveraging MeetC2 are currently observed in the wild, its design represents an evolution in C2 tactics that could be adopted by advanced threat actors to conduct espionage, data exfiltration, or lateral movement within networks.

For European organizations, MeetC2 poses a significant threat due to its ability to evade traditional network defenses and blend malicious activity with legitimate cloud service usage. Organizations relying heavily on Google Workspace, including Google Calendar, are particularly vulnerable to this technique. The stealthy communication channel could facilitate persistent access by attackers, enabling prolonged espionage campaigns or ransomware deployments without easy detection. Confidentiality is at risk as attackers could use this channel to exfiltrate sensitive data or receive commands to manipulate or destroy data. Integrity and availability could also be compromised if attackers use the framework to deploy destructive payloads or disrupt services. Given the widespread adoption of Google services across European enterprises, especially in sectors such as finance, technology, and government, the potential impact is broad. Moreover, the difficulty in detecting such covert channels increases the risk of prolonged undetected intrusions, which can lead to significant financial losses, reputational damage, and regulatory penalties under frameworks like GDPR.

To mitigate the risks posed by MeetC2, European organizations should implement advanced monitoring of cloud API usage, specifically focusing on anomalous patterns in Google Calendar API calls. Behavioral analytics and anomaly detection tools can help identify unusual event creation or modification patterns that deviate from normal user behavior. Organizations should enforce strict access controls and least privilege principles for service accounts and API credentials associated with Google Workspace. Implementing endpoint detection and response (EDR) solutions capable of monitoring process behaviors and network connections can help detect suspicious activities related to MeetC2. Network segmentation and zero trust principles should be applied to limit lateral movement if an endpoint is compromised. Additionally, organizations should conduct regular threat hunting exercises focusing on cloud service abuse and educate security teams about emerging C2 techniques leveraging legitimate cloud platforms. Finally, maintaining up-to-date incident response plans that include scenarios involving cloud API abuse will improve readiness against such threats.