A 515K Shopping Combo List is a large file of stolen email and password pairs primarily used for automated credential stuffing and account takeovers. These compressed,, often dated,, text-based lists target e-commerce accounts to steal personal data and, frequently, contain malware for unsuspecting users. For a detailed technical discussion on this topic, see the discussion on StackExchange security.stackexchange.com. Combolists and ULP Files on the Dark Web - Group-IB