What is Credential Stuffing? | Credential Stuffing Attack

Credential stuffing is a type of cyberattack in which attackers use lists of compromised credentials to gain unauthorized access to user accounts.

Credential stuffing is a type of cyberattack usually performed with bots in which attackers use lists of compromised user credentials, typically consisting of usernames and/or email addresses and the corresponding passwords, to gain unauthorized access to user accounts through large-scale automated login requests.

Unlike credential cracking, credential stuffing attacks do not attempt to brute force or guess passwords - the attacker simply automates the logins for a large number of previously discovered credential pairs. These attacks are possible because many users reuse the same username/password combination across multiple sites. Additionally, many websites lack proper defenses, such as bot management or other security techniques, making them vulnerable to such attacks.

How Credential Stuffing Works

To execute a credential stuffing attack, cybercriminals first obtain stolen username/password pairs, often from large data breaches or by purchasing credentials on the dark web. The attacker then uses an account checker tool to test the stolen credentials against many websites, usually starting with high-value targets like banks, online marketplaces, and streaming services.

If any logins are successful, the attacker knows they have a valid set of credentials. They can then drain the account of stored value, make fraudulent purchases, steal sensitive data, or sell the validated credentials to other bad actors.

While the success rate of credential stuffing attacks is typically low (0.1-0.2% on average), the sheer volume of login attempts means a single attack campaign can compromise thousands of accounts. Attackers often use botnets to distribute the attacks and evade detection.

The Impact of Credential Stuffing

Credential stuffing attacks can have severe consequences for both businesses and consumers:

  • Account takeovers: Successful attacks lead to unauthorized access and account takeovers. Attackers can steal personal data, financial information, make purchases, etc.
  • Reputational damage: Data breaches from credential stuffing erode customer trust and tarnish a company’s reputation.
  • Financial losses: Businesses face increased expenses from chargebacks, customer reimbursement, and increased support costs.
  • Fines and legal issues: Failure to protect customer data can result in fines and legal troubles, especially under regulations like GDPR.

Defending Against Credential Stuffing

Preventing credential stuffing requires effort from both businesses and consumers. Some key defenses include:

For Businesses

  • Implementing multi-factor authentication (MFA) greatly reduces the risk of account takeovers by requiring a second factor like a one-time code, improving login security even if credentials are compromised.
  • Monitor for anomalies: Use tools to detect signs of credential stuffing attacks, like spikes in failed logins, logins from unusual locations/devices, etc.
  • Use CAPTCHAs and rate limiting: CAPTCHAs can help prove login attempts are from real users. Rate limiting can help stop large-scale automated attacks.
  • Deploy a Bot Management solution: Bot management can identify and block malicious traffic like credential stuffing attempts.

For Consumers

  • Use unique passwords and never reuse the same password across multiple accounts. Password managers can help generate and securely store unique, strong passwords.
  • Enabling two-factor authentication adds a second authentication factor to prevent unauthorized access, even if someone compromises your password.
  • Regularly monitor for breaches by checking if your login credentials have been exposed in data breaches using tools like HaveIBeenPwned. If so, change your password immediately.

The Bottom Line

Credential stuffing is a significant and growing threat. As more of our lives move online and bot attacks become common, the potential attack surface expands.

By understanding how these attacks work and implementing proper defenses, businesses and consumers can reduce the risk of falling victim. Adopting security modernization solutions and monitoring for breaches are critical to protecting accounts and meeting compliance requirements.

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