Data leaks of this magnitude usually originate from or database breaches . When a major service is compromised, hackers aggregate the data into "combolists." These lists are then traded or sold on the dark web.
: This indicates the quantity of credentials, specifically 346,000 entries. 346k mail access valid hq combolist mixzip new
: Integrated into Chrome and Android, this tool alerts you if your saved passwords have been found in a data breach. Data leaks of this magnitude usually originate from
: If you receive a notification that a service you use has been breached, change your password immediately—and ensure that password isn't used anywhere else. : Integrated into Chrome and Android, this tool
: A widely trusted site where you can enter your email to see a history of known breaches involving your data.
: "HQ" stands for high quality. In this context, "valid" claims that the credentials have been checked and are currently working.
Possessing or distributing "combolists" containing stolen data is illegal in many jurisdictions under cybercrime laws (such as the CFAA in the US). These lists are the product of criminal activity and are used to facilitate identity theft and financial fraud.