Backdoor.Win32.PROTON.THCBDBO

April 03, 2020
 ALIASES:

Trojan:Win32/Occamy.C (Microsoft); RDN/Generic.dx (McAfee)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size:

293,376 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Apr 2020

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 adds the following processes:

  • attrib +H %System Root%\COVID-19
  • reg.exe ADD HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v disabletaskmgr /t REG_DWORD /d 1 /f
  • reg.exe ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 0 /f
  • reg.exe ADD HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v wallpaper /t REG_SZ /d %System Root%\COVID-19\wallpaper.jpg /f
  • reg.exe ADD HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop /v NoChangingWallPaper /t REG_DWORD /d 1 /f
  • reg.exe ADD HKCU\Control Panel\Cursors /v Arrow /t REG_SZ /d %System Root%\COVID-19\cursor.cur /f
  • reg.exe ADD HKCU\Control Panel\Cursors /v AppStarting /t REG_SZ /d %System Root%\COVID-19\cursor.cur /f
  • reg.exe ADD HKCU\Control Panel\Cursors /v Hand /t REG_SZ /d %System Root%\COVID-19\cursor.cur /f
  • reg.exe ADD HKLM\Software\Microsoft\Windows\CurrentVersion\Run /v CheckForUpdates /t REG_SZ /d %System Root%\COVID-19\Update.vbs /f
  • reg.exe ADD HKLM\Software\Microsoft\Windows\CurrentVersion\Run /v explorer.exe /t REG_SZ /d %System Root%\COVID-19\run.exe /f
  • reg.exe ADD HKLM\software\Microsoft\Windows\CurrentVersion\Run /v GoodbyePC! /t REG_SZ /d %System Root%\COVID-19\end.exe /f
  • shutdown -r -t 5

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

It creates the following folders:

  • %System Root%\COVID-19

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

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
wallpaper = "%System Root%\COVID-19\wallpaper.jpg"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
ActiveDesktop
NoChangingWallPaper = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Run
CheckForUpdates = "%System Root%\COVID-19\Update.vbs"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Run
explorer.exe = "%System Root%\COVID-19\run.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Run
GoodbyePC! = "%System Root%\COVID-19\end.exe"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
disabletaskmgr = "1"

Dropping Routine

This Backdoor drops the following files:

  • %System Root%\COVID-19\run.exe
  • %System Root%\COVID-19\wallpaper.jpg
  • %User Temp%\Update.vbs
  • %User Temp%\run.exe
  • %User Temp%\mainWindow.exe
  • %User Temp%\wallpaper.jpg
  • %System Root%\COVID-19\mainWindow.exe
  • %System Root%\COVID-19\end.exe
  • %System Root%\COVID-19\Update.vbs
  • %User Temp%\end.exe
  • %System Root%\COVID-19\cursor.cur
  • %User Temp%\cursor.cur

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

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.850

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

Identify and terminate files detected as Backdoor.Win32.PROTON.THCBDBO

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware. Screen reader support enabled.

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • EnableLUA = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • wallpaper = "%System Root%\COVID-19\wallpaper.jpg"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop
    • NoChangingWallPaper = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run
    • CheckForUpdates = "%System Root%\COVID-19\Update.vbs"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run
    • explorer.exe = "%System Root%\COVID-19\run.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run
    • GoodbyePC! = "%System Root%\COVID-19\end.exe"

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %System Root%\COVID-19\run.exe
  • %System Root%\COVID-19\wallpaper.jpg
  • %User Temp%\Update.vbs
  • %User Temp%\run.exe
  • %User Temp%\mainWindow.exe
  • %User Temp%\wallpaper.jpg
  • %System Root%\COVID-19\mainWindow.exe
  • %System Root%\COVID-19\end.exe
  • %System Root%\COVID-19\Update.vbs
  • %User Temp%\end.exe
  • %System Root%\COVID-19\cursor.cur
  • %User Temp%\cursor.cur

Step 6

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.
  • %System Root%\COVID-19

Step 7

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.PROTON.THCBDBO. 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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