What Is Credential Stuffing in Cyber Security

Learn what credential stuffing is in cyber security, how it works, and why it’s a growing threat. Discover how attackers exploit reused passwords and how to prevent these automated login attacks.

Aiswarya N Aiswarya N
 Jun 2, 2025
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What Is Credential Stuffing in Cyber Security
What Is Credential Stuffing in Cyber Security

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Cyber security threats in 2025 are becoming more sophisticated, and one such growing concern is credential stuffing. This type of attack is affecting users and businesses worldwide, often leading to serious data breaches and financial losses. With the increasing number of data leaks and poor password practices, credential abuse has become a major tool for cybercriminals. 

In this guide, we will discuss how credential stuffing works, why it’s important, and the best practices to prevent it, helping you stay protected.

What Is Credential Stuffing in Cyber Security?

Credential stuffing in cyber security is a type of automated login attack where hackers use stolen username and password combinations to gain unauthorized access to user accounts across various websites or platforms. These credentials are typically obtained from previous data breaches and then tested on different sites, exploiting the fact that many people reuse passwords.

Unlike traditional hacking methods that rely on guessing passwords, credential stuffing attacks leverage real credentials from prior security breaches, making them more difficult to detect and significantly more dangerous.

The impact of such attacks is substantial. In 2025, the average cost of a data breach reached $4.65 million, marking a 15% increase over the past five years, largely due to the rise of increasingly sophisticated cyber attacks, as reported by IBM Security

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Why Is Credential Stuffing Important?

Understanding credential stuffing is crucial because it’s rapidly becoming one of the most common cyber security threats today. These attacks take advantage of password reuse vulnerabilities, where users rely on the same login credentials across multiple websites and services.

When attackers successfully carry out credential stuffing attacks, the consequences can be severe:

  • Account takeover attacks, giving hackers full access to personal or business accounts
  • Financial fraud, including unauthorized purchases or transactions
  • Identity theft and misuse of personal data
  • Business data breaches, which can seriously damage customer trust and a company’s reputation

One major example is when over 500,000 Zoom accounts were compromised, not because Zoom was hacked, but because attackers used login credentials leaked from other sites. Similarly, services like Netflix, Spotify, and Facebook have also been hit by bot-driven attacks using stolen credentials, affecting millions of users.

Adding to the urgency, Cybersecurity Ventures reports that global cybercrime costs are expected to reach $10.5 trillion annually by 2025, with data breaches being a significant part of this growing financial burden. Given the billions of login details exposed each year, attackers have easy access to massive credential databases, making credential stuffing in cyber security a top concern for individuals and organizations alike.

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How Credential Stuffing Works

Credential stuffing works by using stolen login details, often from data breaches, and testing them on multiple sites with automated bots. If users reuse passwords, attackers can gain access to multiple accounts. To understand the threat better, let’s explore how credential stuffing works:

1. Data Breach

A large-scale data breach exposes usernames and passwords from platforms like e-commerce or social media sites. These credentials are often sold or shared on the dark web, making them available to cybercriminals.

2. Credential Collection

Stolen credentials are traded on the dark web. Since many users reuse passwords, these credentials become valuable for hackers to target multiple accounts.

3. Bot Attack Launch

Cybercriminals use automated bots to test these credentials across different websites. The bots can attempt millions of logins per minute, making it difficult for security systems to catch them all.

4. Successful Login

If users have reused passwords, attackers can gain access to other accounts. This makes it easier for them to steal data, make fraudulent purchases, or carry out other malicious activities

Because many people use the same password for multiple services, this technique is highly effective. This is a clear example of cyber attacks using stolen credentials that exploit user habits and system weaknesses.

How to Detect Credential Stuffing?

Detecting credential stuffing can be difficult because attackers often mimic real users. However, here are signs that may help identify it:

  • A spike in failed login attempts, this suggests bots are testing multiple credentials rapidly.
  • Logins from unusual IP locations or devices.
  • Sudden rise in account lockouts.
  • High traffic to login endpoints, often from a single geographic region or IP range.

Many organizations use threat detection tools and machine learning algorithms to monitor these patterns. Behavioral analytics can also help detect unusual login behaviors that indicate automated activity.

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How to Prevent Credential Stuffing

Preventing credential stuffing requires a mix of technical and user-focused measures. Here are the most effective strategies:

a. Multi-Factor Authentication (MFA)

MFA adds an extra layer of security beyond just a password. Even if attackers have the correct credentials, they can’t log in without the second verification step like a code sent to a phone or email. Enabling multi-factor authentication significantly reduces the risk of account breaches. 

In fact, credential stuffing attacks were responsible for approximately 10% of data breaches in 2024, highlighting the urgent need for stronger authentication practices.

b. CAPTCHA & Rate Limiting

Adding CAPTCHAs during login attempts and limiting the number of login tries per IP can slow down or stop automated bots. These techniques are key in blocking large-scale login attempts used in credential stuffing.

c. Credential Monitoring Tools

Organizations should use tools that monitor the dark web for leaked credentials and notify users to change passwords when their data is found. This proactive step can help prevent hackers from using stolen logins.

d. User Awareness

Educating users to avoid reusing passwords and encouraging the use of password managers can prevent password reuse vulnerabilities. Since credential stuffing relies heavily on reused credentials, breaking this habit is essential.

e. Bot Protection Tools

Using security solutions like web application firewalls (WAF) or bot detection tools can block or slow down automated login attacks. Akamai's 2024 report revealed that there are approximately 26 billion credential stuffing attempts per month, marking a dramatic increase over the past 18 months. This shows how essential robust bot protection has become.

Credential stuffing in cyber security is a serious and growing threat. It takes advantage of human habits and automation to breach accounts without even breaking passwords. By understanding how it works and implementing proper defenses, individuals and organizations can significantly improve their security posture and stay protected. 

In short, credential stuffing is a growing cyber security threat that exploits reused usernames and passwords from previous data breaches. These automated attacks can result in serious consequences such as account takeovers, financial fraud, and identity theft. 

To mitigate the risk, it’s essential for both individuals and organizations to implement strong security measures, such as multi-factor authentication, regular password updates, bot protection, and user awareness. By taking proactive steps, businesses and users can better protect themselves from the dangers of credential stuffing and secure their online accounts against potential threats.

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