Analysis by: Marfel Tiamzon

 PLATFORM:

Windows XP, 2000, 2003, Vista

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 64,904 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Sep 2010

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_TARODRP.SM

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Session Manager
PendingFileRenameOperations = \??\C:\WINDOWS\ntshrui.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Session Manager
AllowProtectedRenames = 1

Other Details

This Trojan does the following:

  • It checks if the current user has admin rights in the system. If the user of the system has no admin rights, it then checks the startup folders of the system by getting the data of the value "Startup" in the following registry entry:
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders
  • It then checks if the running process on the system is %User Profile%\Start Menu\Programs\Startup\Adobe_u.exe. If yes, it creates the following file:
    • %User Profile%\netui0.dll - detected as BKDR_GOLPECO.A
  • The dropped file is then injected to explorer.exe.
  • If %User Profile%\Start Menu\Programs\Startup\Adobe_u.exe is not the running process, it copies itself in the startup folder as follows:
    • %User Profile%\Start Menu\Programs\Startup\Adobe_u.exe
  • It then performs the following command to delete the currently running file:
    • %User Profile%\Start Menu\Programs\Startup\Adobe_u.exe –s {executed malware file}
  • If the user of the system has admin rights, it checks for the existence of the following key:
    • HKEY_Local_Machine\Software\Jiangmin
  • It then drops the following file:
    • %User Profile%\ntshrui.dll - copy of netui0.dll, detected as BKDR_GOLPECO.A
  • It then sets the timestamp of the dropped file using the timestamp of the normal %System%\ntshrui.dll.
  • It creates the following registry keys so to copy its component file to %Windows% and load it as normal system file once the system starts up:
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\??\C:\Documents and Settings\WinXP\ntshrui.dll
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\??\C:\Documents and Settings\WINDOWS\ntshrui.dll

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

  SOLUTION

Minimum Scan Engine: 8.900

Step 1

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by TROJ_DROPPER.QVA

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_DROPPER.QVA

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\SYSTEM\CurrentControlSet\Control\Session Manager
    • PendingFileRenameOperations = \??\C:\WINDOWS\ntshrui.dll
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
    • AllowProtectedRenames = 1

Step 6

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\??\C:\Documents and Settings\WinXP
    • ntshrui.dll
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\??\C:\Documents and Settings\WINDOWS\
    • ntshrui.dll

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPER.QVA 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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