Analysis by: Cris Nowell Pantanilla

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This Trojan connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 2,453,504 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 May 2015
Payload: Modifies files, Connects to URLs/IPs

Arrival Details

This Trojan may be downloaded from the following remote sites:

  • {BLOCKED}la7qwv37qj.onion
  • {BLOCKED}la7qwv37qj.tor2web.org

Installation

This Trojan drops the following files:

  • %Application Data%\tox.log - list of encrypted files.

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

It drops the following non-malicious files:

  • %User Startup%\tox.html - Ransom Note

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

It creates the following folders:

  • %Application Data%\tox_tor

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • toxcrypt

Autostart Technique

This Trojan drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\Tox.exe - copy of itself.

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Download Routine

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

  • http://www.{BLOCKED}l.com/open_source/?download=curl_742_1.zip
  • http://{BLOCKED}t.{BLOCKED}ject.org/torbrowser/4.5.1/tor-win32-0.2.6.7.zip

Other Details

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

  • http://{BLOCKED}nkssujglja.onion
  • http://{BLOCKED}xg64t5wnt.onion
  • http://{BLOCKED}6jut2rupu4.onion

It encrypts files with the following extensions:

  • .txt
  • .odt
  • .ods
  • .odp
  • .odm
  • .odb
  • .doc
  • .docx
  • .docm
  • .wps
  • .xls
  • .xlsx
  • .xlsm
  • .xlsb
  • .xlk
  • .ppt
  • .pptx
  • .pptm
  • .mdb
  • .accdb
  • .pst
  • .dwg
  • .dxf
  • .dxg
  • .wpd
  • .indd
  • .cdr
  • .jpg
  • .jpe
  • .jpeg
  • .dng
  • .arw
  • .mef
  • .mrw
  • .nef
  • .nrw
  • .orf
  • .raf
  • .raw
  • .rwl
  • .ptx
  • .pef
  • .srw
  • .der
  • .cer
  • .rtf
  • .mdf
  • .dbf
  • .psd
  • .pdd
  • .eps
  • .crt
  • .pem
  • .pfx
  • .pdf
  • .odc
  • .srf
  • .bay
  • .crw
  • .dcr
  • .kdc
  • .erf
  • .png
  • .xml
  • .sql
  • .php
  • .asp
  • .aspx
  • .css
  • .cpp
  • .hpp
  • .java
  • .class
  • .veg
  • .aep
  • .aepx
  • .blend
  • .prproj
  • .cad
  • .tif
  • .sitx
  • .sit
  • .rmvb
  • .bmp
  • .pps
  • .pub
  • .qbb
  • .swf
  • .asf
  • .dss
  • .qxd
  • .cdl
  • .mswmm
  • .eml
  • .csv

It renames encrypted files using the following names:

  • {original filename and extension}.toxcrypt

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.694.09
FIRST VSAPI PATTERN DATE: 27 May 2015
VSAPI OPR PATTERN File: 11.695.00
VSAPI OPR PATTERN Date: 27 May 2015

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

Identify and terminate files detected as TROJ_CRYPTOX.SM

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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. %Application Data%\tox_tor

Step 4

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.
%Application Data%\tox.log
%User Startup%\tox.html

Step 5

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