What Makes Credential Stuffing Difficult to Detect?

This report describes credential stuffing attacks: large-scale automated misuse of stolen usernames and passwords driven by widespread password reuse and billions of compromised credentials. It summarizes the threat landscape, provides statistics on prevalence and impact, cites high-profile incidents (e.g., 23andMe and Uber), and recommends mitigations such as credential hashing, breached-password detection, anomaly detection, MFA, and passwordless approaches.