Analysis by: Alyssa Christelle Ramos
ALIASES:

TrojanDownloader:W97M/Bartallex(MICROSOFT);W97M.Downloader(NORTON)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

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: 199,168 bytes
File Type: DOC
Memory Resident: No
Initial Samples Received Date: 11 Apr 2021
Payload: Connects to URLs/IPs, 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.

Dropping Routine

This Trojan drops the following files:

  • If connection to the provided URL is successful:
    • If OS version is Windows 2000, XP, and Server 2003:
      • %User Temp%\17055.bat
      • %User Temp%\17055.vbs
    • If OS version is Windows Vista, 7, 8, and above:
      • %User Temp%\17055.bat
      • %User Temp%\17055.ps1
      • %User Temp%\17055.vbs

    (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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

    Download Routine

    This Trojan accesses the following websites to download files:

    • http://{BLOCKED}r.info/tmp/1623871254.txt
    • http://{BLOCKED}r.info/tmp/lns.txt

    As of this writing, the said sites are inaccessible.

    Other Details

    This Trojan does the following:

    • The document contains the following message details luring users to enable macro content:
    • If connection is successful, it replaces the old content of the document and displays the following:
    • If connection is successful, it adds the following process:
      • cmd.exe /c %User Temp%\17055.bat

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.718.05
FIRST VSAPI PATTERN DATE: 14 May 2021
VSAPI OPR PATTERN File: 16.719.00
VSAPI OPR PATTERN Date: 15 May 2021

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • Downloader.VBA.TRX.XXVBAF01FF015

Step 2

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 3

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 4

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%\17055.bat
  • %User Temp%\17055.ps1
  • %User Temp%\17055.vbs

Step 5

Scan your computer with your Trend Micro product to delete files detected as Trojan.W97M.DLOADR.TIOIBENH. 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 the following Trend Micro Support pages for more information:


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