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TROJ_ENCRYPTED.A

October 08, 2012
 Analysis by: Karl Dominguez
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: Yes

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This malware searches for specific file types in all drives. Once the files are found, it encrypts these files and then renames them.

This Trojan executes certain actions WITHIN the affected computer.

  TECHNICAL DETAILS

File Size:

10,752 bytes

File Type:

PE

Memory Resident:

Yes

Payload:

Drops files, Modifies files, Displays message/message boxes

Installation

This Trojan drops the following copies of itself into the affected system:

  • %User Temp%\4b46etpwM3i3Uxj.exe

(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.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.ENCRYPTED!!!

HKEY_CLASSES_ROOT\QVWTIJBJKUJDOEN

It adds the following registry entries:

HKEY_CLASSES_ROOT\.ENCRYPTED!!!
(default) = QVWTIJBJKUJDOEN

HKEY_CLASSES_ROOT\QVWTIJBJKUJDOEN
(default) = CRYPTED!

HKEY_CLASSES_ROOT\QVWTIJBJKUJDOEN\DefaultIcon
(default) = %User Temp%\4b46etpwM3i3Uxj.exe,0

HKEY_CLASSES_ROOT\QVWTIJBJKUJDOEN\shell\
open\command
(default) = %User Temp%\4b46etpwM3i3Uxj.exe

Other Details

This Trojan displays the following message boxes:



It executes the following:

  • Searches for following file types in all drives:
    • *.zip
    • *.rar
    • *.jpg
    • *.jpeg
    • *.psd
    • *.cdr
    • *.dwg
    • *.max
    • *.bmp
    • *.gif
    • *.png
    • *.doc
    • *.docx
    • *.xls
    • *.xlsx
    • *.ppt
    • *.pptx*.txt
    • *.pdf
    • *.djvu
    • *.htm
    • *.html
    • *.mdb
    • *.cer
    • *.pfx
    • *.kwm
    • *.pwm
    • *.mdf
    • *.dbf
    • *.odt
    • *.vob
    • *.mov
    • *.mpeg
    • *.mpg
    • *.flv
    • *.avi
    • *.wmv
    • *.divx
    • *.mkv
    • *.wav
    • *.flac
    • *.pst
  • Encrypts found files and renames them using the following format:
    • {original file name}.{extension}.ENCRYPTED!!!

  SOLUTION

Minimum Scan Engine:

8.900

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_ENCRYPTED.A

[ 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 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_CLASSES_ROOT
    • .ENCRYPTED!!!
  • In HKEY_CLASSES_ROOT
    • QVWTIJBJKUJDOEN

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_ENCRYPTED.A. 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 5

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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