Credential Stuffing

Credential stuffing is a type of cyberattack where attackers use lists of compromised user credentials (usernames and passwords) to gain unauthorized access to user accounts through large-scale automated login requests. This attack relies on the fact that many people reuse the same usernames and passwords across multiple websites and online services.

Attackers first obtain leaked usernames and passwords from one source. These credentials often come from data breaches at various companies and are typically sold or shared on the Dark Web|dark web. Using automated tools, attackers then attempt to log in to other websites or services with these credentials. This is usually done on a large scale, testing thousands or even millions of username/password combinations across various sites.

When a login attempt is successful, attackers gain unauthorized access to users' accounts. They can then exploit these accounts for various purposes, such as stealing personal information, committing fraud, or spreading spam.

The main reason credential stuffing is effective is due to the common practice of password reuse. Many users use the same password across multiple sites, so a breach on one site can lead to compromised accounts on others. Attackers use sophisticated tools that can automate the login process, allowing them to test millions of credentials relatively quickly and with minimal effort.