Credential Stuffing

🔓 What Is Credential Stuffing?

Credential stuffing is an automated attack in which criminals use large lists of stolen usernames and passwords — obtained from previous data breaches — to try logging into other websites and services. Because many people reuse the same password across multiple accounts, attackers rely on the fact that credentials leaked from one site will also work on others. Automated tools can test millions of username-password pairs against hundreds of websites in a very short time. If even a small percentage of attempts succeed, the attacker gains access to banking, email, shopping, or social media accounts. Credential stuffing is distinct from brute-force attacks: instead of guessing random passwords, attackers use real credentials that are already known to work somewhere.

🧪 Real-World Example

A large gaming platform suffers a data breach, and the stolen logins are posted on a hacking forum. Attackers run those same email-and-password combinations against a popular online retailer. Thousands of accounts are compromised within hours — not because the retailer was hacked, but because users had reused the same passwords.

🛡️ How to Protect Yourself

• Use a unique, strong password for every account — never reuse passwords across sites
• Use a password manager to generate and store complex passwords without needing to memorize them
• Enable multi-factor authentication (MFA) on every account that supports it
• Check sites like HaveIBeenPwned.com to find out if your credentials have appeared in a known breach
• Change passwords immediately for any account associated with a breached service
• Watch for unexpected login notifications or activity alerts from your accounts