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W2KM_BARTALEX.CE

March 18, 2015
 Analysis by: Homer Pacag
 ALIASES:

W97M/Downloader.aeo (McAfee), Troj/DocDl-EU (Sophos),

 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:

Via email

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

  TECHNICAL DETAILS

File Size:

88,064 bytes

File Type:

DOC

Memory Resident:

No

Initial Samples Received Date:

17 Mar 2015

Payload:

Connects to URLs/IPs, Downloads files

Arrival Details

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

NOTES:

Once the malicous document is opened, the macro which contains the malware code executes and drops the following files:

  • For OS Verion XP and below:
    • %Temp%\adobeacd-update.bat
    • %Temp%\adobeacd-updatexp.vbs
  • For OS Version Vista and above:
    • %User Temp%\adobeacd-update.vbs
    • %User Temp%\adobeacd-update.bat
    • %User Temp%\adobeacd-update.ps1

The file adobeacd-updatexp.vbs and adobeacd-update.ps1 accesses the following links to download files:

  • http://{BLOCKED}c.su/5425274.png (For OS Version XP and below)
  • http://{BLOCKED}c.su/5423226.png (For OS Version Vista and above)
  • http://{BLOCKED}.{BLOCKED}.254.213/ca/file.jpg

The malware saves the file using the following filename:

  • %Temp%\444.exe - For OS Verion XP and below (Detected as TROJ_HANCITOR.CE)
  • %User Temp%\444.exe - For OS Verion Vista and above (Detected as TROJ_HANCITOR.CE)
  • %User Temp%\444.jpg - For OS Version Vista and above

For OS Version XP and below, the file adobeacd-update.bat executes adobeacd-updatexp.vbs and the downloaded file %Temp\444.exe%. It also deletes itself after execution.

For OS Version Vista and above, the file adobeacd-update.bat executes adobeacd-update.vbs which ,in turn, executes adobeacd-update.ps1. The file adobeacd-update.ps1 ensures that the downloaded file is executed and deletes all dropped files after execution.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.542.06

FIRST VSAPI PATTERN DATE:

16 Mar 2015

VSAPI OPR PATTERN File:

11.542.06

VSAPI OPR PATTERN Date:

16 Mar 2015

Step 1

Remove the malware/grayware file that dropped/downloaded W2KM_BARTALEX.CE. (Note: Please skip this step if the threat(s) listed below have already been removed.)

     TROJ_HANCITOR.CE

Step 2

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

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.
  • %Temp%\adobeacd-update.bat (For OS Version XP and below)
  • %Temp%\adobeacd-updatexp.vbs (For OS Version XP and below)
  • %User Temp%\adobeacd-update.vbs (For OS Version Vista and above)
  • %User Temp%\adobeacd-update.bat (For OS Version Vista and above)
  • %User Temp%\adobeacd-update.ps1 (For OS Version Vista and above)

Step 4

Scan your computer with your Trend Micro product to delete files detected as W2KM_BARTALEX.CE. 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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