Analysis by: John Donnie Celestre
ALIASES:

VBS/TrojanDownloader.Agent.PHZ trojan (NOD32), Trojan.GenericKD.31039961 (BITDEFENDER)

 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: 4,815 bytes
File Type: Script
Initial Samples Received Date: 24 Jul 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 adds the following processes:

  • %System Root%\Users\Public\Documents\fix.exe

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

Download Routine

This Trojan saves the files it downloads using the following names:

  • %System Root%\Users\Public\Documents\32f.zip

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

It downloads a possibly malicious file from a certain URL. The URL where this malware downloads the said file depends on the following parameter(s) passed on to it by its components:

  • hxxp://a.{BLOCKED}ae.tk/32f.zip

Other Details

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

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.416.06
FIRST VSAPI PATTERN DATE: 01 Aug 2018
VSAPI OPR PATTERN File: 14.417.00
VSAPI OPR PATTERN Date: 02 Aug 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\Documents\32f.zip

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADER.VSNTK. 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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