Credential Stuffing

Credential Stuffing is an attack where stolen username and password pairs (from previous data breaches) are used to try and gain access to accounts on other websites. It relies on the common habit of password reuse across multiple services.

This attack doesn't require guessing passwords. Instead, it automates login attempts using known credentials in bulk. Credential stuffing is highly effective if users reuse passwords across different platforms.

Variants

• Automated stuffing: Bots try thousands of credential pairs against login portals.
• Credential spraying: Tries a few common passwords across many accounts to avoid detection.

Impact

Successful credential stuffing can lead to account takeovers, financial theft, and identity fraud. For organizations, it can result in user data leaks, reputation damage, and regulatory penalties.

Discoverability

These attacks can be hard to detect, especially if attackers space out their login attempts and mimic normal traffic. Monitoring for unusual login patterns and implementing multi-factor authentication (MFA) are key to prevention.

Tools

• Sentry MBA: A tool often used for credential stuffing with built-in configurations for many websites.
• Snipr: Another automation tool for credential reuse attacks.
• OpenBullet: Highly configurable tool for testing credentials at scale.