New macOS XCSSET Variant Targets Firefox with Clipper and Persistence Module
Sep 26, 2025
Malware / Browser Security
Cybersecurity researchers have discovered an updated version of a known Apple macOS malware called XCSSET that has been observed in limited attacks. "This new variant of XCSSET brings key changes related to browser targeting, clipboard hijacking, and persistence mechanisms," the Microsoft Threat Intelligence team said in a Thursday report. "It employs sophisticated encryption and obfuscation techniques, uses run-only compiled AppleScripts for stealthy execution, and expands its data exfiltration capabilities to include Firefox browser data. It also adds another persistence mechanism through LaunchDaemon entries." XCSSET is the name assigned to a sophisticated modular malware that's designed to infect Xcode projects used by software developers and unleash its malicious capabilities when it's being built. Exactly how the malware is distributed remains unclear, but it's suspected that the propagation relies on the Xcode project files being shared amo...