HEROIC Analysts Found 1.6M Leaked Records in YAHOO NEW PART 52

YAHOO NEW PART 52: What HEROIC Analysts Found

On 10-Dec-2022, HEROIC threat analysts identified a combolist titled "YAHOO NEW PART 52" shared by a Telegram user. The file contained an enormous 1,605,237 records combining email addresses, plaintext passwords, and the URLs of the accounts they belong to. The name and scale of this file suggest it was built specifically around Yahoo-linked email accounts, bundled as part of a larger series of similar leaks.

Why This Is Dangerous

With more than 1.6 million records in plaintext, this is one of the largest single combolist files HEROIC analysts have logged in this batch. Attackers can run every one of these email-and-password pairs against login pages automatically, and because the URLs are already attached, they know exactly where to point each attempt. At this scale, even a small percentage of successful logins still means tens of thousands of compromised accounts.

What Was Exposed

• Email addresses
• Plaintext passwords
• Associated account URLs

Why This Matters

A leak of this size is a goldmine for credential stuffing, the technique attackers use to test stolen logins against banking portals, retailers, and other email providers. Because these passwords are stored in plaintext, they can be used immediately, and any password reuse across other accounts multiplies the damage. The end result for victims can be account takeover, identity theft, and financial fraud, often before they even realize their information was exposed.

How Combolists Work

A combolist is a large text file where each line pairs a login identifier, usually an email address, with its matching password. These files are frequently assembled from older breaches, phishing campaigns, and malware infections, then sorted, cleaned, and labeled by the type of account they target before being shared on Telegram and dark web forums. Files numbered as "parts," like this one, usually indicate they belong to a larger series being distributed in batches.

Check If You Are Affected

If you have ever had a Yahoo email account or reused a Yahoo password elsewhere, it is worth checking whether your details appear in this leak. HEROIC's free breach scanner searches a database of more than 400 billion leaked records, including large combolists like YAHOO NEW PART 52, so you can find out in seconds and take action to protect your accounts.