Unit 42 researchers conducted a deep-dive analysis of XCSSET v40, a sophisticated macOS malware that targets software developers through infected Xcode projects. The malware, dubbed the 'Xcode Assassin', has returned in a new version with updated capabilities. Unit 42 leveraged advanced pattern matching techniques and AI-assisted analysis to decode the malware's obfuscated logic and understand its behavior. XCSSET spreads by embedding malicious code into Xcode projects, potentially allowing it to propagate through developer supply chains when infected projects are shared. The analysis highlights the ongoing threat XCSSET poses to the macOS developer ecosystem and underscores the need for heightened vigilance among developers using Xcode.