Credential stuffing is an automated attack method where cybercriminals take lists of usernames and passwords leaked from data breaches and test them against other online services. The attacker uses software tools to rapidly try thousands of credential pairs across different websites, exploiting the common habit of reusing passwords across accounts.
The attack works because many people use the same email address and password combination for multiple services. When one website experiences a data breach, attackers harvest those credentials and immediately test them on banking sites, email providers, social media platforms, and retail accounts. Even a small percentage of successful logins can grant fraudsters access to valuable accounts.
Why it matters: Credential stuffing poses a significant risk to both individuals and organisations. For users, successful attacks can lead to identity theft, financial fraud, and unauthorised access to sensitive personal data. For businesses, these breaches damage customer trust, trigger regulatory fines, and require expensive incident response efforts.
Common targets include:
- Email and cloud storage accounts
- Financial institutions and payment services
- Subscription streaming platforms
- Social media networks
- Online retail and shopping sites
What you can do: Use unique, strong passwords for each online account so a breach at one service cannot compromise your other accounts. Enable multi-factor authentication whenever available, as this blocks attackers even if they obtain your password. Monitor your accounts for suspicious activity and use a reputable password manager to generate and store complex credentials safely.