Description

Trend Micro has identified a new malware, UNAPIMON, utilized by the Earth Freybug threat activity cluster, a subset of the China-linked APT41 cyber espionage group. Operating since at least 2012, Earth Freybug targets organizations globally, employing a blend of living-off-the-land binaries (LOLBins) and custom malware, alongside tactics such as DLL hijacking and API unhooking. This activity shares similarities with Operation CuckooBees, a previously disclosed campaign targeting technology and manufacturing firms across East Asia, Western Europe, and North America. The attack chain begins innocuously with the use of VMware Tools' legitimate executable ("vmtoolsd.exe"), manipulated to create a scheduled task deploying malicious files. Notably, UNAPIMON is deployed via a series of batch files, exploiting a service to load a nonexistent library for DLL side-loading. This technique injects UNAPIMON into critical system processes, evading detection. The malware, written in C++, employs Detours, an open-source Microsoft library, to prevent monitoring of its child processes, enhancing stealth. Trend Micro underscores the sophistication of UNAPIMON, praising the author's coding acumen and innovative use of off-the-shelf libraries. This attack highlights the adaptability of Earth Freybug's tactics, proving the effectiveness of even basic techniques when skillfully applied. Such evolution poses challenges for detection and emphasizes the need for robust cybersecurity measures.