Massive Cyber Campaign Targets 80,000 Microsoft Entra ID Accounts Using Open-Source TeamFiltration Tool

TL;DR

Cybersecurity researchers have uncovered a major account takeover (ATO) campaign targeting over 80,000 Microsoft Entra ID accounts. The campaign leverages TeamFiltration, an open-source penetration testing framework, to compromise user accounts across hundreds of organizations. This ongoing threat underscores the need for enhanced security measures in cloud environments.

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Massive Cyber Campaign Targets Microsoft Entra ID Accounts

Cybersecurity experts have identified a widespread account takeover (ATO) campaign that utilizes an open-source penetration testing framework known as TeamFiltration to compromise Microsoft Entra ID accounts. This campaign, dubbed UNK_SneakyStrike by Proofpoint, has targeted over 80,000 user accounts across numerous organizations¹.

The Scope and Impact of the Campaign

The campaign has affected hundreds of organizations’ cloud tenants, highlighting the significant risk posed by such attacks. TeamFiltration is a powerful tool originally designed for ethical hacking and security testing. However, its open-source nature has made it accessible to malicious actors, who are now exploiting it to breach Microsoft Entra ID accounts.

Understanding TeamFiltration

TeamFiltration is an open-source framework used for penetration testing. It was initially developed to help security professionals identify and mitigate vulnerabilities in cloud environments. The tool’s capabilities include:

• Credential Harvesting: Extracting user credentials from various sources.
• Privilege Escalation: Gaining higher-level access within compromised systems.
• Data Exfiltration: Stealing sensitive information from targeted accounts.

The misuse of TeamFiltration in this campaign underscores the dual-use nature of many cybersecurity tools. While intended for legitimate purposes, these tools can be weaponized by threat actors to conduct unauthorized activities².

Mitigation Strategies

To protect against such attacks, organizations should implement the following measures:

• Multi-Factor Authentication (MFA): Enforce MFA to add an extra layer of security to user accounts.
• Regular Security Audits: Conduct frequent security audits to identify and address potential vulnerabilities.
• Employee Training: Educate employees about phishing attacks and other social engineering techniques.
• Monitoring and Alerts: Use advanced monitoring tools to detect and respond to suspicious activities in real-time.

Conclusion

The UNK_SneakyStrike campaign serves as a reminder of the ongoing threat posed by cyber attacks. As open-source tools like TeamFiltration continue to be misused, it is crucial for organizations to stay vigilant and proactive in their security measures. By implementing robust defenses and staying informed about emerging threats, businesses can better protect their digital assets.

References

1. (2025). “Over 80,000 Microsoft Entra ID Accounts Targeted Using Open-Source TeamFiltration Tool”. The Hacker News. Retrieved 2025-06-12. ↩︎

2. (2025). “TeamFiltration”. Wikipedia. Retrieved 2025-06-12. ↩︎