FortiGuard Labs has traced a hacker group's evolving campaigns across Asia, starting with Winos 4.0 attacks in Taiwan and expanding to Japan and Malaysia. The group employs phishing emails with malicious PDFs and evolving malware delivery tactics. They've shifted from using cloud storage links to custom domains for malware distribution. The latest campaign in Malaysia uses a multi-stage attack flow, leveraging the Windows Task Scheduler for stealth. The malware, identified as HoldingHands, has been updated with new features, including the ability to update C2 IP addresses via registry entries. The attackers have demonstrated adaptability in their techniques while maintaining some consistent patterns, allowing researchers to link seemingly unrelated attacks.
A malware campaign using fake software installers to deliver Winos v4.0, a memory-resident malware, has been tracked throughout 2025. The campaign, dubbed Catena, employs trojanized NSIS installers, reflective DLL loading, and shellcode-embedded INI files to evade detection. It stages payloads entirely in memory, connecting to attacker-controlled servers mainly in Hong Kong. The operation appears focused on Chinese-speaking environments and shows signs of long-term planning by a capable threat group. The infection chain involves multiple stages, including initial NSIS installers, first-stage loaders, and second-stage payloads, ultimately delivering the Winos v4.0 stager. The campaign has evolved over time, adapting its tactics to avoid detection while maintaining core infrastructure and execution logic.
