In a troubling development for cybersecurity professionals, over 80,000 Microsoft Entra ID accounts across hundreds of organizations worldwide have been targeted in a sophisticated password-spraying campaign.

This attack, which has been ongoing since at least December 2024, leverages an open-source penetration testing tool known as TeamFiltration to execute account takeover (ATO) attempts, with several accounts already compromised.

The scale of this campaign, dubbed UNK_SneakyStrike by some security researchers, underscores the persistent vulnerabilities in cloud-based identity management systems. According to TechRadar, the attackers are not relying on bespoke malware or highly complex exploits but instead are exploiting readily available tools to systematically test common passwords across a vast number of accounts. This method, known as password spraying, avoids triggering account lockouts by using a low-and-slow approach, making it particularly insidious and difficult to detect.

A Tool Turned Weapon

What makes this attack particularly concerning for industry insiders is the use of TeamFiltration, a framework originally designed for legitimate penetration testing. As reported by BleepingComputer, hackers have repurposed this tool to automate password-spraying attacks, targeting Microsoft Entra ID accounts—formerly Azure Active Directory—which serve as the backbone for identity and access management in countless enterprise environments. The ease of access to such tools on open-source platforms raises critical questions about the balance between security testing and the potential for misuse.

The impact of these attacks is not merely numerical; it represents a significant risk to organizational security. TechRadar notes that compromised accounts can provide attackers with a foothold into cloud tenants, potentially leading to data breaches, lateral movement within networks, or even full tenant takeovers. For organizations relying on Microsoft’s cloud ecosystem, this serves as a stark reminder of the importance of robust authentication mechanisms.

Defensive Gaps and Industry Implications

Password-spraying attacks exploit a fundamental weakness: the human tendency to reuse passwords or choose predictable ones. Despite years of advocacy for multi-factor authentication (MFA) and passwordless solutions, adoption remains inconsistent across industries. The Hacker News highlights that hundreds of cloud tenants have been affected, suggesting that many organizations may lack the necessary defenses or monitoring to detect such low-volume, distributed attacks.

Microsoft has long emphasized the importance of configuring Entra ID with strong security policies, as seen in past guidance from Microsoft Threat Intelligence posts on social media platforms like X. Yet, the persistence of these attacks indicates that many enterprises are still playing catch-up. Security teams must prioritize anomaly detection, enforce MFA universally, and educate users on password hygiene to mitigate these risks.

Looking Ahead: A Call to Action

As the UNK_SneakyStrike campaign continues unabated, the cybersecurity community faces a dual challenge: countering the immediate threat and addressing the broader systemic issues that enable such attacks. Industry leaders must advocate for stricter controls on the distribution of dual-use tools like TeamFiltration while investing in advanced threat detection powered by artificial intelligence and machine learning.

For now, organizations using Microsoft Entra ID should remain on high alert. Regularly auditing account activity, enforcing complex password policies, and deploying real-time monitoring solutions are no longer optional but essential. The stakes are high, and as TechRadar warns, users and administrators alike must be on their guard to prevent further compromises in an increasingly hostile digital landscape.