Credential Stuffing Defined and How does Credential Stuffing Work to compromise accounts?

What is Credential Stuffing, and how to protect your business from bots attempting to login.

In cybersecurity, credentials are defined as the username login and password or token needed to access the service. Credentials stuffing is a specialist cybersecurity attack which uses bots to test username and password combinations across a wide range of websites and applications. Why do the bots do this?

Quite simply, because humans tend to re-use their passwords, and the fraudsters can readily purchase millions of stolen credential pairs that can be tested on other domains. Once the successful credential pair successfully logins, this fresh validated credential is used as part of more sophisticated account takeover (ATO) attacks. Once in the authenticated domain, the fraudsters can then cause havoc from within the compromised account. Typically bot driven attacks change the existing address and contact details to buy and divert goods and services using stored card details, steal bonus points or loyalty and gift card balances, as well as applying for additional services, loans and other credit items. 

In the diagram you can readily see the size of the problem. The top 12 world wide breaches by the number of stolen records show around 10 Billion stolen credentials for major brands that most consumers will have used. According to a PC Magazine survey, 35% of users simply never change their password, using the same credentials on all sites.

Top Twelve Data Spills 2004-2021 by Records Stolen
At its core, credential stuffing is a cyber attack that preys on individuals who reuse passwords across multiple online platforms. Cybercriminals exploit this vulnerability by using automated tools to systematically test login credentials stolen from one service on multiple other platforms.

The process is deceptively simple yet highly effective. Once a hacker gains access to a set of usernames and passwords, they employ automated scripts to try these combinations on various websites, banking on the fact that users often reuse passwords across different accounts.

The Impact of Credential Stuffing

Individual Consequences

Individual personal accounts, from social media to email, may be compromised, leading to identity theft, financial loss, and potential privacy violations. Most companies have password rotation and some other forms of MFA or authentication, but for smaller companies that don’t, logging into business accounts with credentials that have been compromised is a significant risk.

Business Ramifications

Credential stuffing can lead to unauthorized access to user accounts, jeopardizing customer trust, and tarnishing the company's reputation. Moreover, it poses a significant financial threat through potential legal actions and loss of clientele. Persistent credential stuffing is a major administrative headache. Even though the financial rewards for the hackers may be insignificant, the business will probably spend much more on trying to prevent these attacks.

Detecting and Preventing Credential Stuffing

Multi-Factor Authentication (MFA)

Implementing MFA adds an additional layer of security, requiring users to provide more than just a password for authentication. This makes it significantly more challenging for attackers to gain unauthorized access.

AI Based Traffic Monitoring and Bot Protection

Constantly monitoring login activities and employing anomaly detection systems can help identify unusual patterns, signaling potential credential stuffing attempts. VerifiedVisitors constantly examines the key login paths for signs of bot activity, and prevents the bots from accessing your login paths.Stopping the bots before they can have change to verify the credentials stops these attacks in their track.


Credential stuffing is a silent threat that exploits a common human tendency—password reuse. Understanding its workings, impact, and implementing robust preventive measures is essential for both individuals and businesses. In the ever-evolving cybersecurity landscape, staying one step ahead is the key to safeguarding digital identities.

At VerifiedVisitors, we are committed to empowering businesses with the knowledge and tools to stay one step ahead in the ever-evolving landscape of cybersecurity. 

To get protected today, please visit our portal and get started here.

Frequently Asked Questions

Can using a strong password prevent credential stuffing?

While a strong, unique password is essential, the real defence is to provide robust bot protection on your login paths and adopt a rigorous password update policy.

How do cybercriminals obtain login credentials for credential stuffing?

Cybercriminals often acquire login credentials through data breaches, phishing attacks, or purchasing them on the dark web.

Does changing passwords regularly protect against credential stuffing?

Regularly changing passwords is a good practice, but the key is to avoid reusing passwords across different accounts.

How quickly can a business detect a credential stuffing attack?

With advanced AI based monitoring and anomaly detection systems, businesses can detect credential stuffing attacks BEFORE they can have a chance to login.