The AuthQuake vulnerability affects over 400 million Office 365 users, exposing them to a brute force attack on Microsoft's multi-factor authentication system through time-based one-time passwords (TOTPs). The vulnerability arises from the lack of proper rate limiting and extended validity period for TOTP codes, allowing attackers to bypass security measures. Organizations are advised to strengthen their authentication systems by moving beyond traditional TOTPs, implementing proper monitoring and alerts, and considering third-party authentication providers. Microsoft acknowledged the issue promptly and deployed a temporary fix followed by a permanent solution, highlighting the importance of regular security audits, strict adherence to security best practices, rapid adoption of stronger authentication methods, and clear incident response procedures.