W2KM_VLOAD.A

May 28, 2015
 Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Spammed via email

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

  TECHNICAL DETAILS

File Size:

39,100 bytes

File Type:

DOC

Memory Resident:

No

Initial Samples Received Date:

30 Jan 2015

Payload:

Drops files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

NOTES:

Once the malicious document is opened, it executes a macro to drop the following files:

Windows Version 5.5 or below:

  • %Temp%\adobeacd-update.vbs
  • %Temp%\adobeacd-update.bat

Above Windows Version 5.5:

  • %User Temp%\adobeacd-update.vbs
  • %User Temp%\adobeacd-update.bat

(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.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

The file "adobeacd-update.vbs" accesses the following link to download a file:

  • http://{BLOCKED}sjkals.zabix.net/444.exe

It saves the file using the following filename:

  • %Temp%\444.exe - version 5.5 or below (detected as BKDR_VAWTRAK.DOKR)
  • %User Temp%\444.exe - above version 5.5 (detected as BKDR_VAWTRAK.DOKR)

It then executes the downloaded file. As a result, malicious routines of the downloaded file are exhibited on the affected system.

The file "adobeacd-update.bat" makes sure that the downloaded file is executed and deletes all dropped files after execution.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.448.06

FIRST VSAPI PATTERN DATE:

30 Jan 2015

VSAPI OPR PATTERN File:

11.449.00

VSAPI OPR PATTERN Date:

31 Jan 2015

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

Remove the malware/grayware file dropped/downloaded by W2KM_VLOAD.A. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • BKDR_VAWTRAK.DOKR

Step 3

Search and delete these files

[ Learn More ]
There may be some component files 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.
  • %Temp%\adobeacd-update.vbs
  • %Temp%\adobeacd-update.bat
  • %User Temp%\adobeacd-update.vbs
  • %User Temp%\adobeacd-update.bat

Step 4

Scan your computer with your Trend Micro product to delete files detected as W2KM_VLOAD.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.


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