It is not the result of a single hack but a "megaleak" compiled from over 2,000 different sources , including historical breaches of platforms like Yahoo , LinkedIn , and Dropbox .
The primary threat from this file is credential stuffing . Malicious actors use these lists to automate login attempts across other unrelated services (like banking or social media), exploiting the fact that many users reuse the same password across multiple accounts. "Collection #1" Data Breach - Cloud Security Alliance (CSA) ExLic_Collection-2019-10.rar
The total series (Collections #1–5) involved approximately 2.2 billion to 2.7 billion records and nearly 1 TB of data. It is not the result of a single