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TROJ_MSIL.WJUK

August 03, 2015
 ALIASES:

Trojan:Win32/Skeeyah.A!bit (Microsoft); Trojan-Dropper.MSIL.Agent.servwv (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Generic13_c.ALCD (AVG)

 PLATFORM:

Windows

 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:

118,784 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

03 Aug 2015

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 copies of itself into the affected system:

  • %User Temp%\file__3.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

  • %User Temp%\filesys_mic3
  • %User Profile%\Application Data\love_4
  • %User Temp%\sys_4
  • %User Temp%\wormy4
  • %User Profile%\Application Data\love_3
  • %User Temp%\sys_3
  • %User Temp%\wormy3
  • %User Profile%\Application Data\love_2
  • %User Temp%\sys_2
  • %User Temp%\wormy1

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %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 System Modifications

This Trojan modifies the following file(s):

  • %Application Data%\GDIPFONTCACHEV1.DAT

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

It deletes the following files:

  • %User Temp%\sys_3\pop3.txt
  • %User Temp%\sys_3\im.txt
  • %User Temp%\sys_3\txt_all_love2.txt
  • %User Temp%\file__3.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
GDIPlus
FontCachePath = "%Application Data%"

(Note: The default value data of the said registry entry is %User Profile%\Local Settings\Application Data.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\sys_4\LY_LY4.exe
  • %User Temp%\sys_3\LY_LY3.exe
  • %User Temp%\sys_2\LY_LY2.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.750

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

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_CURRENT_USER\Software\Microsoft\GDIPlus
    • From: FontCachePath = "%Application Data%"
      To: FontCachePath = ""%User Profile%\Local Settings\Application Data""

Step 3

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%\sys_4\LY_LY4.exe
  • %User Temp%\sys_3\LY_LY3.exe
  • %User Temp%\sys_2\LY_LY2.exe

Step 4

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.
  • %User Temp%\filesys_mic3
  • %User Profile%\Application Data\love_4
  • %User Temp%\sys_4
  • %User Temp%\wormy4
  • %User Profile%\Application Data\love_3
  • %User Temp%\sys_3
  • %User Temp%\wormy3
  • %User Profile%\Application Data\love_2
  • %User Temp%\sys_2
  • %User Temp%\wormy1

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_MSIL.WJUK. 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.

Step 6

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %Application Data%\GDIPFONTCACHEV1.DAT

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\sys_3\pop3.txt
  • %User Temp%\sys_3\im.txt
  • %User Temp%\sys_3\txt_all_love2.txt
  • %User Temp%\file__3.exe


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