A China-based cyber espionage campaign is targeting Southeast Asian military targets. The state-sponsored campaign started in 2020.
Palo Alto Networks Unit 42 has been tracking the campaign under the name CL-STA-1087. Here, CL means cluster, and STA means state-backed motivation.
According to security experts Yoav Zemah and Lior Rochberger, “The activity demonstrated strategic operational patience and a focus on highly targeted intelligence collection, rather than bulk data theft. The attackers behind this cluster actively searched for and collected highly specific files concerning military capabilities, organizational structures, and collaborative efforts with Western armed forces.”
About the campaign
The campaign shows traces commonly linked with APT campaigns, such as defense escape tactics, tailored delivery methods, custom payload deployment, and stable operational infrastructure to aid sustained access to hacked systems.
MemFun and AppleChris
Threat actors used tools such as backdoors called MemFun and AppleChris, and a credential harvester called Getpass. Experts found the hacking tools after finding malicious PowerShell execution that allowed the script to go into a sleep state and then make reverse shells to a hacker-controlled C2 server. Experts don't know about the exact initial access vector.
About the attack sequence
The compromise sequence deploys AppleChris’ different versions across victim endpoints and moves laterally to avoid detection. Hackers were also found doing searches for joint military activities, detailed assessments of operational capabilities, and official meeting records. The experts said that the “attackers showed particular interest in files related to military organizational structures and strategy, including command, control, communications, computers, and intelligence (C4I) systems.”
MemFun and AppleChris are designed to access a shared Pastebin account that serves as a dead-drop resolver to retrieve the real C2 address in Base64-encoded format. An AppleChris version also depends on Dropbox to fetch the C2 details via the Pastebin approach, kept as a backup option. Installed via DLL hijacking, AppleChris contacts the C2 server to receive commands to perform drive enumeration and related tasks.
According to Unit 42, “To bypass automated security systems, some of the malware variants employ sandbox evasion tactics at runtime. These variants trigger delayed execution through sleep timers of 30 seconds (EXE) and 120 seconds (DLL), effectively outlasting the typical monitoring windows of automated sandboxes.”