New CleverSoar Malware Attacking Windows Users Bypassing Security Mechanisms

CleverSoar, a new malware installer, targets Chinese and Vietnamese users to deploy advanced tools like Winos4.0 and Nidhogg rootkit. These tools enable keylogging, data theft, security circumvention, and stealthy system control for potential long-term espionage.

It was initially uploaded to VirusTotal in July 2024 and began distribution in November 2024 as an .msi installer, extracting and executing the CleverSoar installer upon installation. 

The installer is designed to target users in China and Vietnam by leveraging fake software or gaming-related .msi installers to infect systems, but it terminates installation if the system language is not Chinese or Vietnamese, indicating a focused attack on these regions.

It shares similarities with the ValleyRAT campaign, suggesting a potential link to the same advanced threat actor, who demonstrates a deep understanding of Windows systems and security tools.

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Deploying the Nidhogg rootkit and Winos4.0 framework disables security measures and selectively targets Chinese and Vietnamese systems to establish persistent backdoor access.

A malicious MSI package likely dropped payloads in “C:\Program Files (x86)\WindowsNT” and ran “Update.exe” with privilege escalation (T1134.002) if not already elevated (checked via GetTokenInformation), and then employs uncommon evasion techniques. 

The malware detects virtual environments by querying the system firmware table for the presence of the “QEMU” string, a common indicator of virtualization previously used by Raspberry Robin, which helps the malware evade analysis and detection.

It bypasses Windows Defender’s emulator checks by using the `LdrGetDllHandleEx`, `RtlImageDirectoryEntryToData`, `NtIsProcessInJob`, and `NtCompressKey` functions, techniques documented in the UACME project, where successful bypass is logged, and the installer proceeds to the next check.

The malware installer verifies the operating system version using the ‘GetVersionExW’ function and checks for the presence of ‘Taskbar.dll’ to distinguish between Windows 10 and Windows 11 systems. 

By restricting non-Microsoft-signed binaries from injecting into processes, it modifies the process mitigation policy, thereby hindering the functionality of certain security solutions that rely on userland hooking techniques. 

It utilizes two anti-debug techniques: timing-based checks, measuring execution delays using ‘GetTickCount64’, and a simple presence check using the ‘IsDebuggerPresent’ API to detect if a debugger is attached to the process.

The malware targets Chinese and Vietnamese systems, creates a registry key, enumerates running processes to identify security software, and attempts to inject malicious code into ‘lsass.exe’ to gain unauthorized privileges, likely for persistence or lateral movement. 

By creating a temporary service, it establishes a persistent ‘CleverSoar’ service, which in turn loads a malicious driver to compromise system security and then enumerates running processes to identify potential targets for further attacks.

According to Rapid7, the CleverSoar installer terminates competing processes, hides files, installs a rootkit, establishes persistence, disables the firewall, and deploys two malicious payloads: a Winos4.0 C2 implant and a custom backdoor, enabling communication with a C2 server.

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