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TROJ_DLOADER.WCN

June 06, 2014
 ALIASES:

Trojan.Win32.Vobfus.ycf (Kaspersky); Mal/Generic-L (Sophos); Trojan.Win32.Generic!BT (Sunbelt); Win32/Heur (AVG)

 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

57,497 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

26 May 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.

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\BITS
WOW64 = "1"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\BITS\Parameters
ServiceDll = "%System%\midimapbits.dll"

(Note: The default value data of the said registry entry is {random values}.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\V3Lites.exe
  • %System%\midimapbits.dll
  • %System Root%\a.dat
  • %Temp%\image.jpg

(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, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}35.42/inf/news1.gif
  • http://{BLOCKED}ata.com/eng/test/jp1.php?{random characters}
  • http://update.{BLOCKED}k.net/ja523.jpg
  • http://www.{BLOCKED}pg.co.jp/bbs/data/update/ja523.jpg
  • http://www.{BLOCKED}int.jp/member/img/ja523.jpg
  • http://www.{BLOCKED}e.net/ja523.jpg
  • http://snsdate.{BLOCKED}t.com/ja523.jpg
  • http://{BLOCKED}ata.com/images/ja523.jpg
  • http://www.{BLOCKED}o.co.jp/ja523.jpg
  • http://www.{BLOCKED}e.com/ja523.jpg
  • http://www.{BLOCKED}n.co.kr/bbs/data/free/ja523.jpg
  • http://www.{BLOCKED}ng.jp/ja523.jpg
  • http://www.{BLOCKED}n.com/ja523.jpg
  • http://www.{BLOCKED}o.jp/ja523.jpg
  • http://www.{BLOCKED}sn.com/ja523.jpg
  • http://www.{BLOCKED}c.jp/ja523.jpg
  • http://www.{BLOCKED}y.com/start/ja523.jpg
  • http://www.{BLOCKED}ble.net/ja523.jpg
  • {BLOCKED}62.18
  • {BLOCKED}.196.132
  • {BLOCKED}0.49.173
  • {BLOCKED}.145.238
  • {BLOCKED}.142.22
  • {BLOCKED}.135.206
  • {BLOCKED}4.241.205
  • {BLOCKED}3.13.21
  • {BLOCKED}.215.210
  • {BLOCKED}.102.42
  • {BLOCKED}5.68.187
  • {BLOCKED}8.153.54
  • {BLOCKED}6.66.188
  • {BLOCKED}6.66.199
  • {BLOCKED}.229.152
  • {BLOCKED}2.222.149
  • {BLOCKED}2.222.169
  • {BLOCKED}2.222.90
  • {BLOCKED}.217.250

It deletes itself after execution.

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

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\ControlSet001\Services\BITS
    • WOW64 = "1"

Step 3

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\SYSTEM\ControlSet001\Services\BITS\Parameters
    • From: ServiceDll = "%System%\midimapbits.dll"
      To: ServiceDll = ""{random values}""

Step 4

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.
  • %User Temp%\V3Lites.exe
  • %System%\midimapbits.dll
  • %System Root%\a.dat
  • %Temp%\image.jpg

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADER.WCN. 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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