A brand new wave of assaults is utilizing the ValleyRAT_S2 malware to quietly break into organizations, keep hidden for lengthy intervals, and steal delicate monetary info.
ValleyRAT_S2 is the second-stage payload of the ValleyRAT household and is written in C++. As soon as inside a community, it behaves like a full distant entry trojan, giving attackers robust management over contaminated methods and a dependable method to transfer knowledge out.
The present marketing campaign spreads primarily via faux Chinese language-language productiveness instruments, cracked software program, and trojanized installers that pose as AI-based spreadsheet mills.
In lots of instances, the malware is delivered via DLL aspect‑loading, the place a professional signed software is tricked into loading a malicious DLL named like a traditional library, equivalent to steam_api64.dll.
After monitoring these operations, APOPHiS recognized ValleyRAT_S2 because the core second-stage backdoor driving these intrusions.
The malware additionally arrives via spearphishing attachments and abused software program replace channels.
Malicious paperwork and archives drop payloads into places just like the Temp folder, for instance:-
C:UsersAdminAppDataLocalTempAI自动化办公表格制作生成工具安装包steam_api64.dll.
From there, Stage 1 focuses on evasion, whereas ValleyRAT_S2 takes over long-term management, system discovery, credential theft, and monetary knowledge assortment.
File information (Supply – Medium)
As soon as lively, ValleyRAT_S2 scans processes, file methods, and registry keys, then reaches out to hardcoded command‑and‑management servers equivalent to 27.124.3.175:14852 over a customized TCP protocol. It could add and obtain recordsdata, run shell instructions, inject payloads, and seize keystrokes.
This makes it well-suited for harvesting on-line banking credentials, cost knowledge, and inside monetary paperwork.
Persistence and watchdog conduct
Probably the most harmful elements of ValleyRAT_S2 is its layered persistence and watchdog design, which helps it survive reboots and guide cleanup.
The malware first phases recordsdata within the consumer’s Temp and AppData paths, creating markers equivalent to %TEMPpercenttarget.pid and configuration paths beneath %APPDATApercentPromotionsTemp.aps.
It additionally abuses Home windows Job Scheduler via COM APIs to re‑run itself on startup, and will use registry run keys for backup startup paths.
Respectable-looking course of (Supply – Medium)
A key function is a generated batch script, monitor.bat, which acts as a watchdog loop.
The script reads the saved course of ID from goal.pid, checks if the primary malware course of remains to be working, and silently restarts it if wanted.
A simplified model seems like this:-
@echo off
set “PIDFile=%TEMPpercenttarget.pid”
set /p pid=<“%PIDFile%”
del “%PIDFile%”
:test
tasklist /fi “PID eq %pid%” | findstr >nul
if errorlevel 1 (
cscript //nologo “%TEMPpercentwatch.vbs”
exit
)
timeout /t 15 >nul
goto test
This loop permits ValleyRAT_S2 to get better if safety instruments or admins kill the primary course of. Mixed with structured exception dealing with, sandbox checks, and course of injection into trusted names like Telegra.exe and WhatsApp.exe, the malware maintains a quiet however robust presence.
For defenders, this implies easy course of killing will not be sufficient; full removing should goal the scheduled duties, batch and VBS watchdog scripts, staged recordsdata, and the backdoor course of abruptly.
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