TROJ_RANSOM.WQ

October 09, 2012
 Analysis by: kathleenno
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Jun 2011

Payload:

Drops files

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%\freeman.exe - also detected as TROJ_RANSOM.WQ
  • %User Temp%\isrcr.exe - also detected as TROJ_RANSOM.WQ
  • %User Temp%\239x5QEd6X0preq.exe - also detected as TROJ_RANSOM.WQ

(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.)

It drops the following copies of itself into the affected system:

  • %System%\wcfgconf.exe

(Note: %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.)

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\Policies\
Explorer\Run
Policies = %System%\wcfgconf.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
wcfgconf = %System%\wcfgconf.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{XR18O8O1-787Y-480T-42EM-OIS0PLFFT5XR}
StubPath = %System%\wcfgconf.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CLASSES_ROOT\SXSHXEFOEMWYOGI\shell\
open\command
(default) = %User Temp%\239x5QEd6X0preq.exe

It adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{XR18O8O1-787Y-480T-42EM-OIS0PLFFT5XR}

HKEY_CLASSES_ROOT\.ENCRYPTED!!!

HKEY_CLASSES_ROOT\SXSHXEFOEMWYOGI

NOTES:

It searches for files with the following extensions in all drives:

  • *.1cd
  • *.3gp
  • *.ac3
  • *.ape
  • *.avi
  • *.bmp
  • *.cdr
  • *.cer
  • *.dbf
  • *.divx
  • *.djvu
  • *.doc
  • *.docx
  • *.dwg
  • *.flac
  • *.flv
  • *.gif
  • *.htm
  • *.html
  • *.ifo
  • *.jpeg
  • *.jpg
  • *.kwm
  • *.m2v
  • *.max
  • *.mdb
  • *.mdf
  • *.mkv
  • *.mov
  • *.mp3
  • *.mp4
  • *.mpeg
  • *.mpg
  • *.odt
  • *.p12
  • *.pdf
  • *.pfx
  • *.png
  • *.ppt
  • *.pptx
  • *.psd
  • *.pst
  • *.pwm
  • *.rar
  • *.txt
  • *.vob
  • *.wav
  • *.wma
  • *.wmv
  • *.xls
  • *.xlsx
  • *.zip

It then encrypts found files and renames them using the following format:

  • {original file name}.{extension}.ENCRYPTED!!!

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.240.02

FIRST VSAPI PATTERN DATE:

22 Jun 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and terminate files detected as TROJ_RANSOM.WQ

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • Policies = %System%\wcfgconf.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • wcfgconf = %System%\wcfgconf.exe

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CLASSES_ROOT
    • .ENCRYPTED!!!
  • In HKEY_CLASSES_ROOT
    • SXSHXEFOEMWYOGI
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {XR18O8O1-787Y-480T-42EM-OIS0PLFFT5XR}

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.WQ. 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 files 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 your computer again.


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