Identity attacks
Credential Stuffing
Credential Stuffing is an attack where attackers use stolen username-password pairs from one breach to attempt login on other accounts. It exploits password reuse: the reality that users use the same password across multiple services.
What Teams Run Into
Detection is harder than prevention. Credential stuffing looks like normal login traffic: someone with valid credentials trying to log in. Distinguishing between a legitimate user and an attacker using stolen credentials requires context and behavioral analysis.
Credential stuffing is fast and cheap. Attackers can test millions of stolen passwords against a service in minutes using botnets. Defense systems get overwhelmed, and some attempts slip through.
Breach notification creates a race condition. When a service is breached, attackers immediately use those credentials on other services before users can change their passwords. The window for damage is measured in minutes.
Why It Matters
Credential Stuffing is a direct consequence of password reuse. If everyone used unique, strong passwords, credential stuffing would fail: a password from service A would be useless on service B. But humans reuse passwords for convenience, turning every breach into a multi-service compromise. Organizations cannot control whether users reuse passwords, but they can deploy MFA to stop credential stuffing from resulting in account takeover.
See Also
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