Brinztech Alert: Large ‘Combo List’ with Weakly Hashed Passwords on Sale

Dark Web News Analysis

A threat actor is selling a large compilation of user credentials, commonly known as a “combo list,” on a popular cybercrime forum. The data, which appears to be aggregated from multiple breaches across several unspecified countries, contains a mix of username/email combinations paired with MD5 hashed passwords, as well as some credentials in plaintext. The low asking price of only $200 makes this data highly accessible to a wide range of malicious actors, from sophisticated groups to low-level opportunists.

This type of list is the primary fuel source for large-scale, automated credential stuffing attacks. The use of the MD5 hashing algorithm is a critical weakness; MD5 is considered cryptographically broken and has been obsolete for years. Passwords hashed with MD5 can be cracked with relative ease using modern hardware and publicly available “rainbow tables.” This effectively means a large portion of the “hashed” passwords in this list can be converted to plaintext by attackers. Criminals purchase these lists to run automated bot attacks against countless websites, testing the credentials to find accounts where users have dangerously reused their passwords.

Key Cybersecurity Insights

This data sale, while generic, highlights a pervasive and fundamental threat to online security:

• High Risk of Mass Credential Stuffing Attacks: The primary and intended use of a “combo list” is for credential stuffing. Automated bots will take the millions of email/password pairs from this list and systematically attempt to log in to thousands of popular websites—including banking, e-commerce, social media, and corporate portals—seeking to take over any accounts that have reused passwords.
• Obsolete MD5 Hashing Enables Easy Password Cracking: MD5 is an outdated and insecure hashing algorithm that offers virtually no protection against modern password cracking techniques. The presence of MD5 hashes in any breached database is a sign of poor, outdated security practices at the original source of the data and means that a significant percentage of the passwords can be easily recovered by attackers.
• Low Price Point Democratizes Cybercrime: The $200 price tag makes this data accessible not just to sophisticated criminal syndicates but also to low-level cybercriminals and novice hackers. This “democratization” of access to stolen credentials leads to a much wider, more unpredictable, and higher volume of attacks across the entire internet.

Mitigation Strategies

In response to the constant threat of credential stuffing fueled by lists like this, universal security best practices are essential for both organizations and individuals:

• Implement Universal Multi-Factor Authentication (MFA): The single most effective defense against credential stuffing is MFA. Organizations must enforce it for their users, and individuals must enable it on all their sensitive online accounts (email, banking, etc.). MFA prevents an attacker from gaining access even if they possess a correct, stolen password.
• Enforce Strong Password Policies and Disallow Known Breached Passwords: Organizations must enforce strong, complex password requirements for their users. More importantly, they should integrate services that check new user passwords against massive databases of known breached credentials to prevent users from choosing a password that is already compromised and circulating in a list like this one.
• Deploy Robust Credential Stuffing Detection and Prevention: All online service providers must deploy technical controls to combat these automated attacks. This includes modern bot detection, implementing CAPTCHA challenges for suspicious logins, rate limiting login attempts from individual IP addresses, and actively monitoring for unusual login patterns that indicate a credential stuffing attack is underway.

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