Analysis by: Rhena Inocencio
ALIASES:

Trojan.Mdropper (Symantec)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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: 45,056 bytes
File Type: Other
Initial Samples Received Date: 25 Jun 2017

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.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}c.{BLOCKED}kura.ne.jp:80/mt/php/0.css
  • http://{BLOCKED}off.net:80/mt/php/0.css
  • http://{BLOCKED}iya.co.kr:80/bbs/imgFd/0.css
  • http://{BLOCKED}b.{BLOCKED}ura.ne.jp:80/menu/0.css

It saves the files it downloads using the following names:

  • {common path of Hanggul Word Processor}\0.css
    • such as %System Root%\HNC\Hwp70\0.css

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Information Theft

This Trojan gathers the following data:

  • Processor Information
  • List of documents (.hwp, .doc, .docx, .xls, .xlsx)
  • List of running services
  • IP configuration
  • Environment Variable values
    • ALLUSERSPROFILE
    • APPDATA
    • CLIENTNAME
    • CommonProgramFiles
    • COMPUTERNAME
    • ComSpec
    • FP_NO_HOST_CHECK
    • HOMEDRIVE
    • HOMEPATH
    • J2D_D3D
    • LOGONSERVER
    • NUMBER_OF_PROCESSOR
    • OS
    • Path
    • PATHEXT
    • PROCESSOR_ARCHITECT
    • PROCESSOR_IDENTIFIE
    • PROCESSOR_LEVEL
    • PROCESSOR_REVISION
    • ProgramFiles
    • PROMPT
    • SESSIONNAME
    • SystemDrive
    • SystemRoot
    • TEMP
    • TMP
    • USERDOMAIN
    • USERNAME
    • USERPROFILE
    • windir

Stolen Information

This Trojan saves the stolen information in the following file:

  • {common path of Hanggul Word Processor}\0.gif
    • such as %System Root%\HNC\Hwp70\0.gif

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}-c.{BLOCKED}ura.ne.jp:80/mt/php/mt2.php
  • http://{BLOCKED}off.net:80/mt/php/lib/function.mbbstring.php
  • http://{BLOCKED}riya.co.kr:80/bbs/imgFd/m1.php
  • http://{BLOCKED}cb.{BLOCKED}ura.ne.jp:80/menu/a_9.php

Other Details

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

NOTES:

It gathers the information by executing commands through cmd.exe.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.884.04
FIRST VSAPI PATTERN DATE: 25 Jun 2014
VSAPI OPR PATTERN File: 10.885.00
VSAPI OPR PATTERN Date: 26 Jun 2014

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

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.  
  • {common path of Hanggul Word Processor}\0.css
  • {common path of Hanggul Word Processor}\0.gif

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_HDROP.AAB. 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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