Backdoor.MSIL.REMCOS.JCASNR

 Analysis by: Jeffrey Francis Bonaobra

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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

It executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

326107136 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Jun 2022

Payload:

Connects to URLs/IPs, Modifies system registry, Collects system information

Arrival Details

This Backdoor 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 Backdoor drops the following copies of itself into the affected system:

  • %Application Data%\fope.exe

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

It drops the following files:

  • %Application Data%\GTX-Vidia\logs.dat → record of user keystrokes
  • %User Temp%\install.vbs
  • %User Temp%\update.vbs

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

  • "cmd.exe" /C schtasks /create /sc minute /mo 1 /tn "Nafdnasia" /tr %Application Data%\fope.exe /f
  • "cmd.exe" /C copy "{Malware File Path}\{Malware File Name}.exe" "%Application Data%\fope.exe"
  • %Windows%\Microsoft.NET\Framework\{.NET Version}\RegAsm.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming 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 creates the following folders:

  • %Application Data%\GTX-Vidia

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

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

  • Mutex_RemWatchDog
  • ewi742dnd-7CE5YY

It injects codes into the following process(es):

  • %Windows%\Microsoft.NET\Framework\{.NET Version}\RegAsm.exe

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

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\ewi742dnd-7CE5YY
exepath = {hex values}

HKEY_CURRENT_USER\Software\ewi742dnd-7CE5YY
licence = {hex values}

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Open and close camera
  • Start and stop keylogger
  • Download files
  • Upload files
  • Delete files
  • Rename files
  • Enumerate files
  • Execute files
  • Browse directory
  • Delete directory
  • Play, pause, and stop an alarm
  • Play, pause, stop, and record audio
  • Change desktop wallpaper
  • Enumerate running processes
  • Execute cmd.exe
  • Manage services (Create, Enumerate, Modify, Start, Stop, and Delete)
  • Manage registry keys and entries (Create, Enumerate, Modify, and Delete)
  • Bypass UAC to escalate its privileges in the victim machine
  • Restarts the affected machine
  • Sleeps the affected machine
  • Logs off the affected machine
  • Shutdown the affected machine
  • Create image
  • Screen capture user's desktop
  • Set, copy, and clear clipboard data
  • Retrieve and clear login data and cookies from the following web browsers:
    • Chrome
    • Firefox
    • Internet Explorer
  • Display a message box
  • Maximize/minimize application
  • Get active program's window title
  • Add, modify, or delete an icon from the taskbar's status area

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • coman-n.{BLOCKED}s.org:30288

However, as of this writing, the said sites are inaccessible.

Information Theft

This Backdoor gathers the following data:

  • User Name
  • Computer Name
  • Product Name
  • Windows Architecture
  • User Keystrokes
  • Locale Information
  • User Privileges (User or Administrator)
  • Clipboard Data
  • Keyboard Input
  • User Activity (Idle Time)
  • Mouse Activity
  • Memory Information
  • System Drive Information

Other Details

This Backdoor adds the following scheduled tasks:

  • Name: Nafdnasia
    Trigger: After triggered, repeat every 00:01:00 indefinitely
    Action: Start a program %Application Data%\fope.exe

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

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.654.05

FIRST VSAPI PATTERN DATE:

28 Jun 2022

VSAPI OPR PATTERN File:

17.655.00

VSAPI OPR PATTERN Date:

29 Jun 2022

Step 1

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 2

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 3

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Nafdnasia - %Application Data%\fope.exe

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 4

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_CURRENT_USER\Software\ewi742dnd-7CE5YY
    • exepath = {hex values}
  • In HKEY_CURRENT_USER\Software\ewi742dnd-7CE5YY
    • licence = {hex values}

Step 5

Delete this registry key

[ 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.

  • HKEY_CURRENT_USER\Software\ewi742dnd-7CE5YY

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.
  • %Application Data%\fope.exe
  • %Application Data%\GTX-Vidia\logs.dat
  • %User Temp%\install.vbs
  • %User Temp%\update.vbs

Step 7

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Application Data%\GTX-Vidia

Step 8

Scan your computer with your Trend Micro product to delete files detected as Backdoor.MSIL.REMCOS.JCASNR. 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 the following Trend Micro Support pages for more information:


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