Analysis by: Kenneth Mcneil Angel
 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.

  TECHNICAL DETAILS

File Size: 9,077 bytes
File Type: VBS
Memory Resident: No
Initial Samples Received Date: 14 Sep 2020
Payload: Connects to URLs/IPs, Downloads files, Collects system information, Executes files

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 creates the following folders:

  • C:\{string2 from the decrypted response from url}

Other Details

This Trojan does the following:

  • It terminates itself when executed in a virtual environment whose computer name is "JOHN-PC" by checking for the following values:
    • OS Model Name
      • Virtual Machine - for Hyper V
      • VMware Virtual Platform - for VMware
      • VirtualBox - for Virtualbox
    • BIOS Version
      • Hyper-V 2008(Beta,RC0,RTM and R2)
      • VS2005/VS2005R2/VS2005R2SP1
      • VPC2004/VPC2007
      • Windows Virtual PC
  • Also terminates itself if the default installed OS language is not in the following list:
    • Spanish – Spain (traditional)
    • Portugese – Brazil
    • Spanish – Mexico
    • Spanish – Spain
    • Spanish Microsoft Office Language – (Microsoft Office Language Value – LANGUAGE_SPANISH)
  • Connects to the following url to download and execute malicious vbscript code in memory to check system and download more files:
    • http://{BLOCKED}.{BLOCKED}7.173/gt21.php
  • If C:\Users\Public\{string1 from the decrypted response from url}4.zip does not exist
    • Connects and decrypts data from http://{BLOCKED}.{BLOCKED}7.173/k1oa.php
    • Connects and downloads file from http://{BLOCKED}.{BLOCKED}7.173/m/k1o{string3 from decrypted data from url}.gt2
    then saves to
    • C:\Users\Public\{string1 from the decrypted response from url}4.zip
  • If C:\Users\Public\{string1 from the decrypted response from url}1.zip does not exist
    • Connects and downloads file from http://{BLOCKED}.{BLOCKED}7.173/k1oa{string1 from the decrypted response from url}.gt2
    then saves it to C:\Users\Public\{string1 from the decrypted response from url}1.zip
    • Connects and downloads file from http://{BLOCKED}.{BLOCKED}7.173/k1oasq.gt2
    • Connects and downloads file from http://{BLOCKED}.{BLOCKED}7.173/k1oasl.gt2
    • Connects and downloads file from http://{BLOCKED}.{BLOCKED}7.173/k1oass.gt2
    • Connects and downloads file from http://{BLOCKED}.{BLOCKED}7.173/k1oaai.gt2
    then saves it to
    • C:\Users\Public\{string1 from the decrypted response from url}sq.zip
    • C:\Users\Public\{string1 from the decrypted response from url}sl.zip
    • C:\Users\Public\{string1 from the decrypted response from url}ss.zip
    • C:\Users\Public\{string1 from the decrypted response from url}ai.zip
  • Extracts the contents of the zip files to the created folder, "C:\{string2 from the decrypted response from url}" and renames them to the following:
    • {string1 from the decrypted response from url} - detected as Trojan.AutoIt.MISPADO.THIADBO
    • {string1 from the decrypted response from url}1.{reversed last 3 characters of string1} - detected as Trojan.Win32.MISPADO.THENC
    • {string1 from the decrypted response from url}ai.exe - non-malicious AutoIt loader
    • libeay32.dll – non-malicious libraries
    • ssleay32.dll – non-malicious libraries
    • winx86.dll – non-malicious libraries
      • then deletes all the downloaded zip files
  • Decrypts and encrypts configuration from code and saves to:
    • C:\Users\Public\{second character of computer name}_
  • Gathers the following data:
    • strings from decrypted response from url
    • created folder path
    • hard-coded values from the script
    • current date
    then encrypts and saves it to
    • C:\Users\Public\{second character of computer name}
  • Executes the following downloaded exe files with arguments:
    • {string1 from the decrypted response from url}ai.exe {string1 from the decrypted response from url} @1
    • {string1 from the decrypted response from url}ai.exe {string1 from the decrypted response from url} ##1
    • {string1 from the decrypted response from url}ai.exe {string1 from the decrypted response from url} ##3
  • Hides the said created folder

    •   SOLUTION

    Minimum Scan Engine: 9.850
    FIRST VSAPI PATTERN FILE: 16.226.06
    FIRST VSAPI PATTERN DATE: 14 Sep 2020
    VSAPI OPR PATTERN File: 16.227.00
    VSAPI OPR PATTERN Date: 15 Sep 2020

    Step 1

    Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

       
      • Downloader.VBS.TRX.XXVBS82EFF006

    Step 2

    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 3

    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 4

    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.
    • C:\Users\Public\{decrypted string1 from url response}sq.zip
    • C:\Users\Public\{decrypted string1 from url response}sl.zip
    • C:\Users\Public\{decrypted string1 from url response}ss.zip
    • C:\Users\Public\{decrypted string1 from url response}ai.zip
    • C:\{decrypted string2 from url response}\{decrypted string1 from url response}
    • C:\{decrypted string2 from url response}\{decrypted string1 from url response}1.{reversed last 3 characters of string1}
    • C:\{decrypted string2 from url response}\{string1 from the decrypted response from url}ai.exe
    DATA_GENERIC
  • Once located, select the file then press SHIFT+DELETE to delete it.
  • Repeat the said steps for all files listed.
    *Note: Read the following Microsoft page if these steps do not work on Windows 7 and Server 2008 (R2).

    • Step 5

    Search and delete these folders

    [ Learn More ]
    Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
    • C:\{decrypted string2 from url response}
    DATA_GENERIC
  • Once located, select the file then press SHIFT+DELETE to permanently delete the folder.
  • Repeat steps 2-3 for the remaining folders:
      DATA_GENERIC
    *Note: Read the following Microsoft page if these steps do not work on Windows 7 and Server 2008 (R2).

    • Step 6

    Scan your computer with your Trend Micro product to delete files detected as Trojan.VBS.MISPADU.THIADBO. 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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