Digital Security Awareness - Credential Stuffing: Password Reuse Leaves Accounts Vulnerable

Credential Stuffing - The Dangers of Password Reuse

Credential stuffing is a common form of cyberattack where attackers use large volumes of stolen login credentials in attempts to gain unauthorized access to user accounts on various websites. The success of this attack relies on individuals reusing the same username and password across multiple accounts.

How it works:

1. A website or service experiences a data breach where user credentials are leaked or stolen.
2. Stolen credentials are compiled into massive lists and sold on the dark web.
3. Attackers use automated tools to attempt logins using across multiple sites.
4. A successful username and password attempts allows account takeover.

Example: an attacker uses a list of leaked usernames and passwords from a recent data breach to attempt logging into a company’s internal systems. By automating login attempts across multiple applications, the attacker seeks to exploit employees who reused their credentials.

Example: cybercriminals target an employee portal by running a credential stuffing attack with stolen login details obtained from a phishing campaign. After gaining access to several accounts, the attacker searches for sensitive information and escalates privileges to further compromise the company.

How is it dangerous

Credential stuffing is particularly dangerous for several reasons. Password reuse is a widespread practice making it easy for attackers to compromise more than one service using a single set of credentials. AI and automation offer the tools needed to programmatically test credentials in the background. They use botnets to rapidly and systematically attempt username and password combinations along with variations across many sites.

Large-scale data breaches have resulted in millions of stolen credentials being readily available for attackers. Another less conspicous outcome is attackers searching leaked credentials lists for credentials belonging to employees of your organization. This can lead to account takeovers, data breaches, and other security incidents right at home.

Password hygiene best practices

Unique password for every account: never reuse the same password.

Multi-factor authentication: enforce the use of multi-factor authentication. Although many providers offer SMS-based MFA, you should prefer to use an authenticator app to prevent account takeover via SIM swap.

Use a password manager: managing multiple unique passwords can be difficult, but password managers make password hygiene trivial.

Monitor accounts: regularly audit accounts for suspicious activity. Enable account notifications, but always verify the authenticity of an alert before responding.

Password changes: password intervals are antiquitated. Only change passwords after a suspected breach.

Watch for breach notifications: check Have I Been Pwned regularly to ensure your credentials haven't been compromised.

Protecting your organization

Credential stuffing is a major threat to businesses that rely on employee or customer logins. Organizations may experience costly data breaches and account takeovers as a result of this type of attack.

Rate limiting and CAPTCHAs: rate limiting restricts the number of login attempts from a single IP address, while CAPTCHAs can stop automated bots from flooding login pages with credential stuffing attempts.

Multi-factor authentication: require MFA on internal user accounts. External users should be strongly encouraged to use MFA as well (best practice requires MFA).

Monitor for unusual login activity: automated tools can detect suspicious patterns allowing businesses to respond to potential attacks in real time.

Educate users: companies should educate their customers and employees about the importance of using unique passwords and MFA to safeguard their accounts.

Use breached password detection: the Have I Been Pwned API can be used to compare your password hashes against known breaches. This can be used to invalidate compromised passwords and force a password reset.

Credential stuffing is a common form of cyberattack that takes advantage of password reuse and large-scale data breaches. It can lead to credential theft and account takeover. Avoid falling victim by arming your organization with the knowledge and tools required to prevent credential stuffing, transforming employees from potential vulnerabilities into a robust line of defense.

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_{This follow-up post is part of a blog series I'm writing called Digital Security Awareness for Non-Technical Professionals.}