Analysis by: Anthony Joe Melgarejo
ALIASES:

Ransom:Win32/Orxlocker.A (Microsoft), Trojan.Cryptolocker.AA (Symantec)

 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 retrieves specific information from the affected system.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 365,568 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 04 Sep 2015
Payload: Encrypts 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 drops the following component file(s):

  • %Desktop%\Payment-instructions.html - ransom note

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • https://www.torproject.org/dist/torbrowser/5.0.1/tor-win32-0.2.6.10.zip - legitimate Tor Application

It saves the files it downloads using the following names:

  • %User Temp%\{random characters}.dat

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Information Theft

This Trojan retrieves the following information from the affected system:

  • Hard Disk Volume Serial number
  • OS information

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}rzmzilheyj.onion/get.php

It encrypts files with the following extensions:

  • .txt
  • .jpg
  • .jpe
  • .gif
  • .png
  • .jpeg
  • .avi
  • .pdf
  • .mp3
  • .mp4
  • .ppt
  • .pptx
  • .xls
  • .xlsx
  • .QBB
  • .QBW
  • .QDB
  • .mp3
  • .mp4
  • .doc
  • .docx
  • .docm
  • .zip
  • .rar
  • .7z
  • .wps
  • .php
  • .ssh
  • .key
  • .psd
  • .tc
  • .dwg
  • .wpd
  • .rtf
  • .raw
  • .pst
  • .wmv
  • .mpeg
  • .mpg
  • .mov
  • .m4v
  • .mkv
  • .vhd
  • .vmdk
  • .vdi
  • .vbox

NOTES:

It attemtps to skip encrypting files in the following directories:

  • C:\Windows.old
  • C:\Windows
  • C:\Program Files
  • C:\Program Files (x86)
  • C:\$Recycle.Bin
  • C:\ProgramData
  • C:\DELL
  • C:\NVIDIA
  • C:\DRIVERS
  • C:\SWSETUP

It appends .LOCKED to the file name of the encrypted files.

It displays the following message box after encrypting the file in the affected system:

The ransom note displays the following:

  SOLUTION

Minimum Scan Engine: 9.750

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.  
  • %Desktop%\Payment-instructions.html
  • %User Temp%\{random characters}.dat

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPORX.SM. 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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