Analysis by: Raighen Sanchez
ALIASES:

Trojan:Win32/Lunam (MICROSOFT), HEUR:Trojan.MSIL.Injects.gen (KASPERSKY)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Virus

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Virus arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It adds infection markers to files.

  TECHNICAL DETAILS

File Size: 533,658 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 17 May 2023
Payload: Encrypts files, Drops files

Arrival Details

This Virus arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Virus drops the following files:

  • %User Temp%\{15 random alphanumeric characters}.exe → original copy of any infected file

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following copies of itself into the affected system:

  • %User Temp%\CTS.exe
  • %Windows%\CTS.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It adds the following processes:

  • %Temp%\{15 random alphanumeric character}.exe
  • %Windows%\CTS.exe

(Note: %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\3pc6RWOgectGTFqCowxjeGy3XIGPtLwNrsr2zDctYD4hAU5pj4GW7rm8gHrHyTB6

Autostart Technique

This Virus adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
CTS = %Windows%\CTS.exe

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
CurrentVersion\Run
CTS = %User Temp%\CTS.exe

File Infection

This Virus infects the following files:

  • %User Profile%\{Filename}.exe
  • {Network / Remote Drive}\{Filename}.exe
  • {Removable Drive}\{Filename}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It infects the following file types:

  • exe

It adds infection markers to files.

Other Details

This Virus does the following:

  • It continuously monitors for .exe files to infect on removable and network / remote drives.
  • It checks if the following virtual machine- or sandbox-related strings are present in the affected system:
    • MALWARE
    • S3 Trio32/64
    • SAMPLE
    • SANDBOX
    • SCHMIDTI
    • USER
    • VirtualBox Graphics Adapter
    • VIRUS
    • VM Additions S3 Trio32/64
    • VMWARE
    • VMware SVGA II
  • It checks if the following virtual machine- or sandbox-related window are present in the affected system:
    • Afx:400000:0 → WinJail Sandbox

It checks if the following virtual machine or sandbox related module(s) is loaded in the affected system:

  • SbieDLL.dll

It checks if the following virtual machine- or sandbox-related registry keys are present in the affected system:

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\
Scsi\Scsi Port 0\Scsi Bus 0\
Target Id 0\Logical Unit Id 0
Identifier = VBOX

HKEY_LOCAL_MACHINE\HARDWARE\Description\
System

HKEY_LOCAL_MACHINE\HARDWARE\Description\
System
VideoBiosVersion = VIRTUALBOX

HKEY_LOCAL_MACHINE\SOFTWARE\Oracle\
VirtualBox Guest Additions

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\
Scsi\Scsi Port 0\Scsi Bus 0\
Target Id 0\Logical Unit Id 0
Identifier = VMWARE

HKEY_LOCAL_MACHINE\SOFTWARE\VMware, Inc.\
VMware Tools

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Disk\Enum
0 = vmware

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Class\4D36E968-E325-11CE-BFC1-08002BE10318\
0000
DriverDesc = VMWARE

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Class\4D36E968-E325-11CE-BFC1-08002BE10318\
0000\Settings
Device Description = VMWARE

HKEY_LOCAL_MACHINE\SOFTWARE\VMware, Inc.\
VMware Tools
InstallPath = C:\PROGRAM FILES\VMWARE\VMWARE TOOLS\

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\
Scsi\Scsi Port 0\Scsi Bus 0\
Target Id 0\Logical Unit Id 0
Identifier = QEMU

HKEY_LOCAL_MACHINE\HARDWARE\Description\
System
SystemBiosVersion = QEMU

It checks if the following virtual machine or sandbox related folder(s) or file(s) is present in the affected system:

  • C:\file.exe

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.460.04
FIRST VSAPI PATTERN DATE: 22 May 2023
VSAPI OPR PATTERN File: 18.461.00
VSAPI OPR PATTERN Date: 23 May 2023

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • PUA.Win32.TRX.XXPE50FFF068

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\CurrentVersion\Run
    • CTS = %Windows%\CTS.exe
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\CurrentVersion\Run
    • CTS = %User Temp%\CTS.exe

Step 6

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Temp%\{15 random alphanumeric characters}.exe
  • %Windows%\CTS.exe
  • %User Temp%\CTS.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Virus.MSIL.MAZEFECT.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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