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W2KM_DLOADR.D

February 18, 2015
 Analysis by: Sammy Chua
 ALIASES:

TrojanDownloader:O97M/Bartallex.A (Microsoft); W97M.Downloader (Symantec); Trojan-Downloader.MSWord.Agent.eq (Kaspersky); W97M/Downloader.acr (McAfee)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

62,976 bytes

File Type:

DOC

Memory Resident:

No

Initial Samples Received Date:

09 Feb 2015

Arrival Details

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

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Dropping Routine

This Trojan drops the following files:

  • c:\Windows\Temp\adobeacd-update.bat - hardcoded directory for Windows XP and below
  • c:\Windows\Temp\adobeacd-updatexp.vbs - hardcoded directory for Windows XP and below
  • c:\Windows\Temp\444.exe - hardcoded directory for Windows XP and below
  • c:\Users\{username}\AppData\Local\Temp\adobeacd-update.ps1 - hardcoded directory for Windows Vista and above
  • c:\Users\{username}\AppData\Local\Temp\adobeacd-update.bat - hardcoded directory for Windows Vista and above
  • c:\Users\{username}\AppData\Local\Temp\adobeacd-update.vbs - hardcoded directory for Windows Vista and above
  • c:\Users\{username}\AppData\Local\Temp\444.exe - hardcoded directory for Windows Vista and above

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.131.29/upd/install.exe

NOTES:
This trojan executes its dropped files.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.470.02

FIRST VSAPI PATTERN DATE:

10 Feb 2015

VSAPI OPR PATTERN File:

11.471.00

VSAPI OPR PATTERN Date:

11 Feb 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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Search and delete these files

[ Learn More ]
There may be some 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.
  • c:\Windows\Temp\adobeacd-update.bat
  • c:\Windows\Temp\adobeacd-updatexp.vbs
  • c:\Windows\Temp\444.exe
  • c:\Users\{username}\AppData\Local\Temp\adobeacd-update.ps1
  • c:\Users\{username}\AppData\Local\Temp\adobeacd-update.bat
  • c:\Users\{username}\AppData\Local\Temp\adobeacd-update.vbs
  • c:\Users\{username}\AppData\Local\Temp\444.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as W2KM_DLOADR.D. 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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