GreedyBear is a sophisticated threat actor responsible for over $1 million in cryptocurrency theft through a campaign involving 150 malicious Firefox extensions, nearly 500 malicious executables, and numerous fraudulent websites. They employ techniques such as 'Extension Hollowing' to replace legitimate extensions with malicious versions that capture wallet credentials. The campaign is centralized, with most malicious domains resolving to a single IP address, and it has expanded to target other browsers while utilizing AI-generated code to enhance scalability and evade detection.