Cybersecurity researchers have uncovered a new account takeover (ATO) campaign that leverages an open-source penetration testing framework called TeamFiltration to breach Microsoft Entra ID (formerly Azure Active Directory) user accounts.
The activity, codenamed UNK_SneakyStrike by Proofpoint, has targeted over 80,000 user accounts across hundreds of organizations’ cloud tenants since a surge in login attempts was observed in December 2024, leading to successful account takeovers.
“Attackers leverage Microsoft Teams API and Amazon Web Services (AWS) servers located in various geographical regions to launch user-enumeration and password-spraying attempts,” the enterprise security company said. “Attackers exploited access to specific resources and native applications, such as Microsoft Teams, OneDrive, Outlook, and others.”