What is Credential Stuffing?
Credential stuffing is an automated cyberattack where stolen username and password pairs (“credentials”) are used to fraudulently gain access to user accounts on various websites. This technique exploits the common habit of reusing passwords across multiple sites. When credentials are exposed through data breaches or phishing attacks, attackers use them to attempt logins on numerous other sites, increasing the chances of successful account takeovers.
How Credential Stuffing Works
Credential stuffing is a specific type of brute force attack. Unlike traditional brute forcing, which involves guessing passwords, credential stuffing uses known, breached username and password pairs to attempt logins on different websites.
Attackers can also exploit information from data leaks to reset passwords, particularly targeting business accounts. Publicly available business information, like phone numbers and email addresses, can be used to answer security questions or leverage recovery emails, enabling attackers to take over accounts even if the passwords aren’t reused.
Likelihood & Severity
Credential stuffing is a prevalent technique for account takeovers. It poses significant risks to both consumers and enterprises due to the cascading effects of these breaches. One compromised account can lead to multiple others being breached through reused credentials.
Anatomy of an Attack
- Acquisition: Attackers obtain usernames and passwords from a data breach, phishing attack, or password dump site.
- Testing: Using automated tools, attackers test the stolen credentials on various websites, such as social media platforms, online marketplaces, or web applications.
- Access: Successful logins indicate valid credentials, allowing attackers to access the accounts.
Once access is gained, attackers may:
- Drain accounts of stored value or make unauthorized purchases.
- Access sensitive information, such as credit card details, private messages, or documents.
- Use the account to send phishing messages or spam.
- Sell valid credentials for other attackers to exploit.
Example Scenario
In a typical scenario, acme.com’s database is breached, and an attacker uses the stolen credentials on multiple other websites. They find that the user “spongebob” has reused their password on two additional sites, and “sally” has reused hers on one site. This allows the attacker to access three more accounts.
Defense Strategies
To defend against credential stuffing, organizations should implement multi-factor authentication (MFA) as a primary countermeasure. Additional resources, such as the Credential Stuffing Prevention Cheat Sheet, provide comprehensive guidelines for mitigating these attacks.
Real-World Examples from 2023-2024
Several large-scale breaches have been attributed to credential stuffing in recent years:
- Marriott International, 2023: Attackers used credential stuffing to gain access to guest loyalty accounts, compromising personal and booking information.
- Source: CyberScoop
- Robinhood, 2023: A credential stuffing attack led to unauthorized access to user accounts, resulting in the exposure of sensitive financial data.
- Source: TechCrunch
- Reddit, 2024: Credential stuffing was used to access user accounts, allowing attackers to post unauthorized content and access private messages.
- Source: The Verge
- Spotify, 2024: A large-scale credential stuffing attack compromised numerous user accounts, with attackers changing passwords and accessing personal playlists and subscription details.
- Source: ZDNet
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