Analysis by: Julie Anne Cabuhat
ALIASES:

Ransom:Win32/FileCryptor (Microsoft), Ransom.VXLock (Malwarebytes), Trojan-Ransom.VxLock (Ikarus)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 19,456 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Jan 2017

Installation

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

  • VXLOCK32_64

Other Details

This Trojan encrypts files with the following extensions:

  • .txt
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .sqlite
  • .odt
  • .jpg
  • .gif
  • .png
  • .csv
  • .sql
  • .mdb
  • .sln
  • .php
  • .asp
  • .aspx
  • .html
  • .xml
  • .psd
  • .xsd
  • .cpp
  • .h
  • .htm
  • .py
  • .reg

It requires the existence of the following files to properly run:

  • {malware path}\RSA_keys.pub
  • {malware path}\RSA_keys.private
  • C:\secret.txt.vxLock
  • %Application Data%\Mozilla\Firefox\Profiles\oqvmaj52.default\blocklist.xml.vxLock

(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 renames encrypted files using the following names:

  • {Original filename and extension}.vxLock

It does the following:

  • It checks if the following module is loaded in its process as an anti-sandbox technique:
    • SbieDLL.dll
  • It uses various APIs as an anti-debugging technique.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.180.06
FIRST VSAPI PATTERN DATE: 25 Jan 2017
VSAPI OPR PATTERN File: 13.181.00
VSAPI OPR PATTERN Date: 26 Jan 2017

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

Restore encrypted files from backup.

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_VXLOCK.A. 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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