Account Takeover Just Got Easier Because of the MarketDownload Breach: 9.7 Million at Risk

HEROIC analysts found the MarketDownload breach data circulating on dark web marketplaces in August 2023, exposing nearly 9.7 million records from the U.S.-based general business platform. The dataset was recieved during routine monitoring of underground forums and immediately stood out for its massive size. What made it particularly alarming was that passwords were stored in plaintext, meaning every single credential in the dump was instantly usable for attacks against other services.

9.7 Million Plaintext Credentials Give Attackers Massive Scale

With nearly 10 million email and plaintext password pairs, attackers have everything they need to run credential stuffing campaigns at industrial scale. Automated tools can test these credentials across thousands of websites simultaneously, targeting banking portals, email accounts, e-commerce sites, and subscription services. Even a one percent success rate on a dataset this large translates to nearly 100,000 compromised accounts on other platforms. The damage from this breach extends far beyond MarketDownload itself.

What Was Exposed in the MarketDownload Breach

• Email addresses
• Plaintext passwords (no hashing or encryption applied)

Why Credential Stuffing From This Breach Is an Ongoing Threat

Credential stuffing attacks powered by the MarketDownload data are not a one-time event. These dumps get traded and resold on underground markets for months or years after the initial leak. Anyone who used their email and password on MarketDownload and reused that combination elsewhere is at risk of account takeover, identity theft, and financial fraud long after the original breach occured. The sheer volume of records also means this data will likely be bundled into future mega-compilation dumps, extending its reach even further.

How Plaintext Password Breaches Happen

When a developer builds a user authentication system without implementing proper password hashing, every password entered by a user goes straight into the database as readable text. If an attacker then gains access to that database through SQL injection, a misconfigured server, or an insider threat, they walk away with a completely accessable list of working credentials. There is no cracking step required. This represents one of the most basic and preventable security failures in web development, yet it continues to appear in breach datasets regularly.

Check If Your Data Was Exposed

HEROIC offers a free breach scanner that searches across 400 billion compromised records. If your email appeared in the MarketDownload breach or any of the thousands of other leaks in our database, you will know immediately and can act before attackers do. Run your free scan at HEROIC.com.