Over 80,000 Microsoft Entra ID Accounts Targeted Using Open-Source TeamFiltration Tool

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.