Infostealers have become the leading cause of identity-based attacks, significantly contributing to ransomware, fraud, and data breaches. This guide outlines how organizations can effectively defend against these threats. It emphasizes the changing nature of the attack surface and highlights the importance of understanding how infostealers function within modern attack chains. These malicious tools are prevalent in underground markets, with specific strains being utilized for various nefarious purposes. One major focus is on how stolen identities are exploited. Criminals use them for a variety of attacks, and organizations need to develop strategies to monitor and respond to these incidents. The guide breaks down practical steps that teams can take to manage their identity attack surface, from recognizing potential vulnerabilities to implementing real-time monitoring solutions. Another critical aspect covered is operationalizing threat intelligence. The guide provides methods to transform security logs into actionable insights. This approach helps organizations close existing security gaps by using data to inform decisions and improve defenses. By adopting these strategies, teams can better protect themselves against the evolving tactics of cybercriminals.