Credential Stuffing

Credential stuffing is an automated attack that uses stolen username-password pairs from data breaches to attempt login on other services. Attackers exploit password reuse across sites, testing thousands of credential combinations per minute using botnets. Defenses include rate limiting, CAPTCHA challenges, multi-factor authentication, breached password detection, and device fingerprinting to identify automated login attempts. URL shortening services are both targets and vectors for credential stuffing. As targets, their user accounts—containing link analytics and redirect control—must be protected with strong authentication. As vectors, attackers use shortened URLs to distribute phishing pages that harvest credentials. Services must implement robust account security while monitoring for links directing to known credential harvesting infrastructure.