BTCstealer4.0 is a clipboard-hijacking tool that monitors a user's clipboard activity. When a Bitcoin address is copied—for instance, during a transaction—the software silently replaces it with an address controlled by the attacker. When the user pastes the address to send Bitcoin, the funds are redirected to the attacker’s wallet instead of the intended recipient, all without the user noticing the swap. The "Mass Address Generator" is a companion tool that creates large numbers of Bitcoin addresses, often paired with their corresponding private keys. These generated addresses are used by the stealer to substitute the victim's copied address, ensuring the attacker has a ready supply of destinations for the funds.