Analysis by: RonJay Kristoffer Caragay
ALIASES:

[3.OLE]:W97M/Downloader (NAI), VBA/TrojanDownloader.Agent.I trojan (NOD32), Trojan-Downloader.VBS.Agent.aik (Kaspersky)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

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.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 534,528 bytes
File Type: DOC, DOCX
Memory Resident: No
Initial Samples Received Date: 11 Jun 2014
Payload: Downloads files, Displays message/message boxes

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.

Download Routine

This Trojan downloads the file from the following URL and renames the file when stored in the affected system:

  • %User Temp%\GSTOUF.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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It connects to the following website(s) to download and execute a malicious file:

  • http://www.{BLOCKED}ti-atelier.com.ar/ingles/wp/ss.exe

As of this writing, the said sites are inaccessible.

NOTES:

This malware includes instructions on how to enable macro settings to deceive users so that the malware routines will run properly.

It displays the following message box that says that the malware is incompatible with the affected system.

  SOLUTION

Minimum Scan Engine: 9.700

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

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.  
  • %User Temp%\GSTOUF.exe

Step 3

Scan your computer with your Trend Micro product to delete files detected as W97M_DLOADR.H. 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 4

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]


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