Credential Stuffing
An attack that uses stolen passwords from one breach to break into your other accounts.
What Is Credential Stuffing?
Credential stuffing is a cyberattack in which criminals use username and password combinations stolen from one data breach to attempt logins on many other websites and services. It works because so many people reuse the same password across multiple accounts, so a single stolen password can unlock far more than the account it came from.
How It Works
The attack begins with stolen credentials. Massive lists of usernames and passwords from past data breaches are bought and traded on criminal marketplaces. Attackers then use automated tools to try these stolen pairs against many other sites at once, from email and banking to business systems.
Because the tools test thousands of credentials rapidly, even a small success rate yields results. Every account where a person reused the breached password becomes vulnerable. The attacker does not need to guess or crack anything; they are simply reusing passwords the victim already exposed elsewhere.
This is why credential stuffing is so effective and so common. It does not rely on breaking your defenses directly. It relies on a password you used somewhere else being exposed in that other service’s breach, then reused on your accounts.
Why It Matters
Credential stuffing turns one breach into many and can lead to account takeover, financial theft, and data loss across your organization. It is a direct consequence of password reuse, which remains extremely common. The two defenses that stop it are straightforward: never reuse passwords, ideally using a password manager, and enable multi-factor authentication everywhere, so a stolen password alone is not enough to get in.
Related Terms
- What Is Multi-Factor Authentication (MFA)?
- What Is a Data Breach?
- What Is the Dark Web?
- What Is a Threat Actor?
For a complete guide, read our full article on why multi-factor authentication matters.
SecTec helps organizations stop credential-based attacks with MFA and access controls as part of our network and endpoint security service.
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