Credential stuffing is a common attack
88% of hacking attacks use leaked credentials. Most of the cyberattacks are noticed too late by users and businesses.
Stolen credentials are hard to detect
Attackers reuse real usernames and passwords to log into accounts. That makes credential stuffing prevention unavoidable.
Best practices to prevent credential stuffing
Users shouldn't reuse passwords. Enterprises should implement multilayered defense with CAPTCHA and MFA.
CAPTCHAs act upstream against credential stuffing
As one layer in a credential stuffing prevention strategy, modern CAPTCHAs like Friendly Captcha, secure websites and user data.
In a credential stuffing attack, stolen usernames and passwords from various data breaches are used on a large scale. Because users often choose the same password for multiple accounts, bots or proxy servers use these passwords on different platforms. This makes it easy for bots.
According to the 2025 Verizon Data Breach Investigations Report, cyber attackers will exploit stolen or brute-forced login credentials in 88% of hacking attacks. Although brute-force attacks and account takeovers are widespread and often noticed by users, credential stuffing often goes unnoticed.
That’s why we want to highlight credential stuffing prevention in this article. How can enterprises prevent credential stuffing attacks without compromising the user experience? Effective credential stuffing mitigation begins with understanding how automation exploits reused passwords. One effective method, that makes credential stuffing harder, is to integrate a CAPTCHA service into websites and interfaces.
Credential Stuffing vs. Brute Force Attacks
What are the differences between credential stuffing and brute force attacks? While both target login systems, credential stuffing attacks rely on stolen credentials and real passwords, making it faster and harder to detect. Brute force attacks involve repeated trial and error to access sensitive user data or encryption keys.
Brute force attackers often use automated tools to guess login details. Credential stuffing, on the other hand, only uses existing usernames and passwords. Credential stuffing attacks in general are more difficult to detect and often evade simple security measures.
That’s why credential stuffing attacks are so effective. There are so many places in the dark web where login details have been leaked, and many users reuse their passwords. Enterprises’ minimal defensive measures give bots free rein here. You can find detailed information on how to prevent brute force attacks in the Learning Center.
| Aspect | Credential Stuffing Attack | Brute Force Attack |
|---|---|---|
|
Definition |
Attackers reuse stolen usernames and passwords obtained from previous security breaches to log into multiple accounts on multiple platforms. |
Attackers repeatedly guess passwords – either sequentially or randomly – until they find the correct one for a particular account. |
|
Attack Method |
Automated bots test the same login credentials on multiple systems. |
Automated tools or scripts try every possible password combination for one account or target list. |
|
Data Source |
Uses leaked credential databases from security breaches (already valid passwords). |
No existing data; relies on password generation algorithms or dictionaries. |
|
Goal |
Gain access to as many existing accounts as possible to commit identity theft. |
Hack a single account by discovering its password to gain unauthorized access. |
|
Success Rate |
High. Weak or reused passwords often work across multiple services. |
Low. it Depends on password strength and lockout policies. |
|
Speed / Efficiency |
Very fast, because it uses valid credentials and distributed botnets. |
Slower; requires significant computing time and triggers rate limits quickly. |
|
Detection Challenge |
Looks like normal logins from legitimate browsers and IP addresses. |
Easy to spot due to failed login attempts on one account. |
|
Typical Indicators |
Many login attempts from different IP addresses using different usernames but identical passwords. |
Multiple login attempts for one username from a single IP address or subnet. |
|
Primary Defense |
CAPTCHA and challenge-response systems to block suspicious activity. |
CAPTCHA, account lockouts, rate limiting, and strong password policies. |
How Credential Stuffing Attacks Work
Because so many stolen login credentials are circulating on the internet, they are very cheap. Attackers purchase these lists at a low price and then pass the information on to credential stuffing bots. Even with a low success rate, these attacks can be profitable.
This is how a credential stuffing attack works:
Attackers collect credential databases from data leaks or the dark web.
A list of login data is then prepared and supplemented with possible username/email and password combinations.
Using bots or proxy servers, attackers carry out automated login attempts across multiple platforms and accounts.
Upon successful login, the account is taken over and misused or the data is resold.
How to Prevent Credential Stuffing Attacks
We have seen how credential stuffing works and the dangers it poses. Now, we will examine ways to prevent future attacks and best bot protection.
How Users Can Prevent Credential Stuffing Attacks
Effective credential stuffing prevention begins with strong credential hygiene and user security awareness. To avoid credential theft, users should follow key cybersecurity best practices. The most important practice is to use a unique password for each account and never reuse credentials across services. Reused passwords make credential stuffing possible, but distinct passwords make these automated attacks nearly impossible.
Using password managers helps users maintain good credential hygiene by securely storing and generating strong, unique passwords. Activating multi-factor authentication (MFA) or passwordless authentication provides an additional safeguard against credential stuffing and other automated account-takeover attempts.
Enterprises can educate employees and strengthen credential stuffing prevention through regular training sessions, phishing awareness training, and workshops with industry experts. Encouraging feedback and innovation in internal forums helps users stay alert to suspicious websites and emerging threats. Building a culture of continuous cybersecurity awareness ensures that both individuals and organizations reduce the risk of credential theft and stay resilient against credential stuffing attacks.
How Enterprises Can Prevent Credential Stuffing Attacks
Any enterprise with a website offering logins, authentication, and payment transactions can be affected by credential stuffing. This is not necessarily related to data breaches at the enterprise itself. Security breaches on other sites can lead to logins on yours. In most cases, data breaches, compromised accounts or compromised login credentials from other companies enable credential stuffing attacks. However, this does not compromise the enterprise’s own security.
Enforce Strong Password Policies
In order to balance security, enterprises should recommend that their users create unique passwords, enforce strong password policies and password blocklists, and use passwordless authentication. Best practices for creating passwords include using passphrases of four or more random words or strong passwords consisting of at least 12 characters, including uppercase and lowercase letters, numbers, and symbols. These password policies form the foundation of credential reuse prevention across your user base. However, it is ultimately impossible to verify whether users and employees comply with these recommendations.
Monitoring and Detection Mechanisms
Some websites implement monitoring tools to evaluate entered passwords against a database of compromised weak or reused passwords before accepting a new registration. Nevertheless, users may reuse a simple password from another service that has not been compromised yet. Another method is to regularly monitor for compromised credentials. This can alert users if their information has been affected by a data breach, prompting them to take immediate action.
Multi-Factor Authentication
For enterprises, multi-factor authentication (MFA) is by far the best defense against the majority of password-related attacks. An MFA can be combined with other security measures such as CAPTCHAs so that a second factor is only required in specific, high-risk circumstances.
Device and Connection Fingerprinting
Some cyber security services provide device and connection fingerprinting to identify and block suspicious login attempts that may be part of credential stuffing attacks. Fingerprinting typically compromises privacy. Therefore, the consequences must be considered in the context of privacy compliance.
CAPTCHA
CAPTCHAs are an easy and effective way to hinder automated credential stuffing attempts from reaching the authentication stage. They distinguish real login attempts from automated login attempts. CAPTCHAs prevent large-scale automated login attacks by increasing the time and computational costs to the point that the attack is no longer profitable. Modern, privacy-first CAPTCHAs run invisibly in the background, providing enterprise login systems with a powerful yet frictionless layer of bot protection.
How To Prevent Credential Stuffing Attacks with Friendly Captcha
Friendly Captcha offers advanced bot protection against sophisticated attacks with cryptographic proof-of-work challenges.The modern bot protection service detects failed login cascades and dynamically adjusts the difficulty level of the invisible puzzle to stop credential stuffing attacks.
Friendly Captcha makes it so difficult for attackers to achieve their goal that it provides reliable protection against credential stuffing attacks. It interrupts the process before login details are validated. This distinguishes bots from real people and secures accounts.
Next-gen CAPTCHA services, such as Friendly Captcha, offer an undisturbed user experience without tracking user behavior. Friendly Captcha reliably detects credential stuffing bot attacks with its cryptographic proof-of-work challenges, and risk-based scaling. Friendly Captcha’s comprehensive data from its large international risk database detects suspicious login attempts in time to prevent major damage.
It is fully accessible and WCAG-compliant while keeping high standards in privacy. Friendly Captcha does not use HTTP cookies or store any sensitive personal information in persistent memory. This makes Friendly Captcha fully compliant with the GDPR as well as other privacy laws.
Stop Credential Stuffing Before It Starts
Preventing credential stuffing is not optional; modern bots make bot protection essential. Users and businesses can protect themselves against credential stuffing attacks and reduce large-scale automated login attempts in various ways.
Although strong passwords and multi-factor authentication are important, they cannot completely stop the automation that drives credential stuffing. As an upstream layer of protection, modern CAPTCHAs, such as Friendly Captcha, can detect malicious credential stuffing bots before stolen login credentials are validated.
Friendly Captcha provides small and large businesses, as well as institutions and organizations, with an invisible, GDPR-compliant, and accessible CAPTCHA solution. It protects sensitive user data, secures login endpoints, and ensures a seamless user experience. Try Friendly Captcha 30 days for free and sign up now!
FAQ
Credential stuffing prevention is the practice of using defensive measures to stop automated cyberattacks that use stolen username and password pairs to gain unauthorized access to online accounts. Because many users reuse the same passwords across different websites, a credential breach on one site can be used to compromise accounts on many others. Bot protection ideally takes effect before credentials are validated, which is only possible with a secure CAPTCHA. Friendly Captcha provides comprehensive protection for your website while remaining user-friendly and compliant with privacy regulations.
To prevent credential stuffing, businesses must implement a multi-layered defense strategy that includes strong authentication methods, bot detection, bot protection, and user education. Since these automated attacks exploit users who reuse passwords, a single solution is rarely enough to protect against them. Modern CAPTCHAs, such as Friendly Captcha, stop automated bots before they can submit stolen credentials, thereby protecting login forms without impacting the user experience.
There is no single “leading” company for credential stuffing prevention, as the best solution depends on a business’s specific needs, size, and existing security infrastructure. Instead, the market is led by several major players in bot management, fraud prevention, and web application security. Friendly Captcha is a leading CAPTCHA provider dedicated specifically to credential stuffing prevention. Its modern cryptographic proof-of-work CAPTCHA technology blocks automated login attempts at their source. This technology distinguishes real users from bots without collecting personal data. Friendly Captcha’s privacy-compliant, WCAG-accessible, GDPR-certified approach makes it one of the most advanced and trusted solutions for enterprises seeking to effectively and ethically block credential stuffing attacks.
The difference between credential stuffingandbrute-force attackslies in the credentials used and the logic of the attack. Credential stuffing uses stolen, valid username and password pairs, relying on victims reusing the same credentials across different sites. In contrast, a brute-force attack is a trial-and-error process that attempts to guess the correct password by systematically trying different combinations. A modern method of protection against credential stuffing is a next-gen CAPTCHA such as Friendly Captcha. With its cryptographic background puzzles and proof-of-work approach, Friendly Captcha detects bots before user data is even validated. Try Friendly Captcha free for 30 days.
The single most effective way to prevent credential stuffing is to block automated login attempts before credentials are validated. Modern CAPTCHA systems that prioritize privacy, such as Friendly Captcha, provide this protection by distinguishing real users from bots without collecting personal data. Combined with good password hygiene and optional multi-factor authentication, CAPTCHAs offer the most effective, low-friction defense against credential stuffing attacks.
Yes, Multi-Factor Authentication (MFA)is one of the most effective and critical defenses against credential stuffing attacks. Since credential stuffing relies on an attacker using a stolen username and password combination, MFA greatly reduces the effectiveness of credential stuffing by adding an extra verification step after entering a password. Even if attackers obtain valid credentials, they cannot access the account without the second factor. However, MFA alone cannot stop automated login attempts; CAPTCHAs are also necessary to block the bots that perform credential stuffing on a large scale. The strongest protection comes from combining modern CAPTCHAs like Friendly Captcha with MFA.
Preventing the exposure of credentials requires a comprehensive strategy that includes proactive technical controls, strong administrative policies, and ongoing user education. Organizations must protect credentials throughout their entire lifecycle, from creation to storage and transmission. Users should avoid reusing passwords, be alert to phishing attempts, and use password managers for secure storage. At the application level, implementing a CAPTCHA prevents bots from repeatedly testing or validating exposed credentials, thus keeping login systems safe and compliant. Next-gen Friendly CAPTCHA can be integrated into almost every system. Check out Friendly Captcha integrations.
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