This threat campaign targets users of Microsoft Teams by abusing the recently introduced 'Chat with Anyone' feature, which allows communication outside an organization's tenant. Threat actors impersonate internal IT support personnel to socially engineer victims into initiating Quick Assist sessions, a Windows remote assistance tool. Once the Quick Assist session is active, attackers deploy an infostealer malware named 'updater.exe' onto the victim's system. The malware facilitates credential theft and may enable further data exfiltration. The attack chain begins with phishing to lure victims, followed by reconnaissance activities to gather system and network information, and culminates in executing malicious code. The use of legitimate collaboration and remote assistance tools helps attackers evade detection and gain trust, increasing the likelihood of success. Indicators include a malicious file hash (5c68baf77938b4aedef90403d6e8b19c9d24c8a9) and a suspicious domain (spextronic.com) used in the campaign. The attack leverages multiple MITRE ATT&CK techniques such as T1566 (phishing), T1204.001 (user execution), T1059 (command execution), and T1078 (valid accounts). The campaign underscores the evolving tactics of threat actors exploiting trusted platforms and social engineering to bypass technical controls. Mitigation recommendations include disabling the 'Chat with Anyone' feature via Teams Messaging Policies, enforcing two-factor authentication, and implementing Zero Trust security models to reduce lateral movement and credential misuse.

For European organizations, this threat can lead to significant credential compromise, enabling attackers to access sensitive systems and data. The use of Quick Assist for remote control can facilitate lateral movement within networks, increasing the risk of data breaches and operational disruption. Credential theft may also lead to unauthorized access to cloud services, email accounts, and internal resources, potentially resulting in intellectual property loss, regulatory non-compliance, and reputational damage. Given the widespread adoption of Microsoft Teams across Europe, especially in sectors like finance, healthcare, and government, the attack could impact critical infrastructure and sensitive personal data protected under GDPR. The social engineering vector increases risk as it targets human factors, which are often the weakest security link. The medium severity rating reflects the attack's reliance on user interaction but acknowledges the high impact of successful credential theft and remote access compromise.

1. Disable the 'Chat with Anyone' feature in Microsoft Teams through Teams Messaging Policies to prevent external unsolicited chats that facilitate social engineering. 2. Enforce multi-factor authentication (MFA) across all user accounts, especially for access to collaboration tools and remote assistance utilities. 3. Implement Zero Trust architecture principles, including strict access controls, continuous monitoring, and least privilege access to limit lateral movement post-compromise. 4. Conduct targeted user awareness training focused on recognizing social engineering tactics involving collaboration tools and remote assistance requests. 5. Monitor and restrict Quick Assist usage via Group Policy or endpoint management solutions to control remote assistance sessions. 6. Employ endpoint detection and response (EDR) solutions to detect execution of known infostealer malware and suspicious processes like 'updater.exe'. 7. Maintain updated threat intelligence feeds to identify and block indicators of compromise such as malicious domains (e.g., spextronic.com) and file hashes. 8. Regularly audit Teams configurations and access logs to detect anomalous activities indicative of social engineering or unauthorized remote sessions.