ALIASES:

Backdoor.Win32.DarkKomet.djdy (Kaspersky)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • 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: 1,085,258 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 20 Aug 2014

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 creates the following folders:

  • %System Root%\Documents and Settings\Wilbert
  • %System Root%\Documents
  • %User Profile%\Application Data\InstallDir
  • %User Profile%\My Documents\MSDCSC
  • %User Profile%\Application Data\dclogs

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
helpthis = "%User Profile%\InstallDir\help.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
helpthis = "%User Profile%\InstallDir\help.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Update = "%User Profile%\MSDCSC\msdcsc.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
UserInit = "%System%\userinit.exe,%User Profile%\MSDCSC\msdcsc.exe"

(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
TUKE

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
TUKE\Recent File List

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
TUKE\Settings

HKEY_CURRENT_USER\Software\DC3_FEXEC

Dropping Routine

This Trojan drops the following files:

  • __tmp_rar_sfx_access_check_148687
  • product.bat
  • product.sfx.exe
  • __tmp_rar_sfx_access_check_156328
  • product.exe
  • %System Root%\Documents\product.exe
  • %User Profile%\MSDCSC\msdcsc.exe
  • %User Profile%\InstallDir\help.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}.238.23

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.700

Step 1

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

Step 2

Identify and delete files detected as TROJ_INJECT.YYPE using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

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_CURRENT_USER\Software
    • Local AppWizard-Generated Applications
  • In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
    • TUKE
  • In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\TUKE
    • Recent File List
  • In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\TUKE
    • Settings
  • In HKEY_CURRENT_USER\Software
    • DC3_FEXEC

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\Microsoft\Windows\CurrentVersion\Run
    • helpthis = "%User Profile%\InstallDir\help.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • helpthis = "%User Profile%\InstallDir\help.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Update = "%User Profile%\MSDCSC\msdcsc.exe"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: UserInit = "%System%\userinit.exe,%User Profile%\MSDCSC\msdcsc.exe"
      To: UserInit = ""%Windows%\system32\userinit.exe,""

Step 6

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.
  • __tmp_rar_sfx_access_check_148687
  • product.bat
  • product.sfx.exe
  • __tmp_rar_sfx_access_check_156328
  • product.exe
  • %System Root%\Documents\product.exe
  • %User Profile%\MSDCSC\msdcsc.exe
  • %User Profile%\InstallDir\help.exe

Step 7

Search and delete these folders

[ 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%\Documents and Settings\Wilbert
  • %System Root%\Documents
  • %User Profile%\Application Data\InstallDir
  • %User Profile%\My Documents\MSDCSC
  • %User Profile%\Application Data\dclogs

Step 8

Scan your computer with your Trend Micro product to delete files detected as TROJ_INJECT.YYPE. 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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