Trojan.Win32.DARKEM.A

October 07, 2022
 Analysis by: Carlos Villegas Madrid
 ALIASES:

Win32:Malware-gen (AVAST)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size:

752,352 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

04 Oct 2022

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %User Temp%\IXP000.TMP\~TMP4352.TMP → Deletes afterwards
  • %User Temp%\IXP000.TMP\hj.png → Deletes afterwards
  • %User Temp%\IXP000.TMP\oi.exe → Deletes afterwards
  • %User Temp%\IXP000.TMP\rl.png → Deletes afterwards
  • %AppDataLocal%\Microsoft\ShellInfo.dll
  • %AppDataLocal%\Microsoft\data.png

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

It adds the following processes:

  • %User Temp%\IXP000.TMP\oi.exe
  • cmd /c cd %AppDataLocal%\Microsoft&&cmd /c reg.exe import data.png
  • cmd /c reg.exe import data.png
  • reg.exe import data.png
  • cmd /c cd %AppDataLocal%\Microsoft&&cmd /c rundll32.exe /sta {A762B0C7-5244-4B3E-ADED-D549E9CEA39E} "Keyboard";
  • cmd /c rundll32.exe /sta {A762B0C7-5244-4B3E-ADED-D549E9CEA39E} "Keyboard";
  • rundll32.exe /sta {A762B0C7-5244-4B3E-ADED-D549E9CEA39E} "Keyboard";

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

Other System Modifications

This Trojan deletes the following folders:

  • %User Temp%\IXP000.TMP → Deletes afterwards

(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 adds the following registry entries:

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Implemented Categories
(Default) = (value not set)

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Implemented Categories\{40FC6ED5-2438-11CF-A3DB-080036F12502}
(Default) = (value not set)

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\InprocServer32
(Default) = %AppDataLocal%\Microsoft\ShellInfo.dll

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\InprocServer32
ThreadingModel = Apartment

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\ProgID
(Default) = ShellInfo.CShellRunDll

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Programmable
(Default) = (value not set)

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\TypeLib
(Default) = (value not set)

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\VERSION
(Default) = 1.0

It modifies the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
wextract_cleanup0 = rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 "%User Temp%\IXP000.TMP\"

Other Details

This Trojan adds the following registry keys:

HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\
{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}
(Default) = ShellInfo.CShellRunDll

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.856.05

FIRST VSAPI PATTERN DATE:

05 Oct 2022

VSAPI OPR PATTERN File:

17.857.00

VSAPI OPR PATTERN Date:

06 Oct 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

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_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Implemented Categories
    • (Default) = (value not set)
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Implemented Categories\{40FC6ED5-2438-11CF-A3DB-080036F12502}
    • (Default) = (value not set)
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\InprocServer32
    • (Default) = %AppDataLocal%\Microsoft\ShellInfo.dll
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\InprocServer32
    • ThreadingModel = Apartment
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\ProgID
    • (Default) = ShellInfo.CShellRunDll
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Programmable
    • (Default) = (value not set)
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\TypeLib
    • (Default) = (value not set)
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\VERSION
    • (Default) = 1.0

Step 4

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.

  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Implemented Categories
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\InprocServer32
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\ProgID
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\Programmable
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\TypeLib
  • In HKEY_USERS\S-1-5-21-2019512041-4230814187-3178073052-1000_CLASSES\CLSID\{A762B0C7-5244-4B3E-ADED-D549E9CEA39E}\VERSION

Step 5

Search and delete this file

[ 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.
  • %AppDataLocal%\Microsoft\ShellInfo.dll
  • %AppDataLocal%\Microsoft\data.png

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.DARKEM.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 the following Trend Micro Support pages for more information:


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