Credential stuffing is a cyberattack where automated bots attempt to log into user accounts using lists of stolen usernames and passwords leaked from other breaches. Since users frequently reuse the same password across multiple sites, these attacks have extremely high success rates.
The Mechanics of a Stuffing Attack
A hacker takes a database dump of a breached site containing millions of email-password pairs. They configure a botnet to systematically try logging into target platforms using these credentials. The bots distribute requests across thousands of rotating residential proxy IPs to bypass basic rate limit rules.
Defending Your Web Gateways
To secure your user accounts, implement a multi-layered defense strategy:
- Rate Limiting by IP and Username: Limit unsuccessful login attempts per IP address and per username. If a specific account has multiple failed attempts in a short window, lock it temporarily.
- Require Multi-Factor Authentication: MFA makes compromised passwords useless. Even if the hacker has the password, they cannot bypass the authenticator code.
- Cross-Reference Compromised Credentials: Use APIs like "Have I Been Pwned" to check passwords during registration or login. If a user attempts to use a known leaked password, force them to change it.
By protecting your authentication gateways, you keep your users safe even when they practice poor password hygiene elsewhere online.