Owning O365 Through Better Brute-Forcing

**Executive Summary:** This report documents practical attacker techniques targeting Office 365, including user-enumeration via Microsoft authentication endpoints and ActiveSync, password-spray and brute-force methods using common and seasonally-themed passwords, tools for automating enumeration and credential harvesting (Office365UserEnum, o365recon), and post-compromise reconnaissance; it concludes with mitigation guidance such as enforcing multi-factor authentication and monitoring for password-spray activity.