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RANSOM_CRYPTESLA.CBQ163V

April 02, 2016
 Analysis by: Rhena Inocencio
 ALIASES:

Trojan-Ransom.Win32.Bitman.vnq (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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.

  TECHNICAL DETAILS

File Size:

184,320 bytes

File Type:

EXE

Initial Samples Received Date:

31 Mar 2016

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 copies of itself into the affected system and executes them:

  • %My Documents%\{random filename}.exe

    (Note: %My Documents% is usually C:\Documents and Settings\{user name}\My Documents on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Documents on Windows Vista and above.)

It drops the following files:

  • {folders containing encrypted files}\+REcovER+{random characters}+.txt
  • {folders containing encrypted files}\+REcovER+{random characters}+.html
  • {folders containing encrypted files}\+REcovER+{random characters}+.png
  • %My Documents%\+REcovER+{random characters}+.txt
  • %My Documents%\+REcovER+{random characters}+.html
  • %My Documents%\+REcovER+{random characters}+.png
  • %My Documents%\recover.bin
  • %My Documents%\+recover+file.txt

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random key name} = "C:\WINDOWS\SYSTEM32\CMD.EXE /C START "" "%My Documents%\{random filename}.exe"

Other System Modifications

This Trojan modifies the following file(s):

  • It encrypts files in all fixed, removable, and network drives and shares.
  • It does not append an extension name to the encrypted files

It adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLinkedConnections = "1"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}mbargada.com/wp-content/plugins/formcraft/php/swift/lib/classes/Swift/Mime/HeaderEncoder/stringfile.php
  • http://{BLOCKED}l.org/wp-content/plugins/js_composer/assets/lib/font-awesome/src/assets/font-awesome/fonts/stringfile.php
  • http://{BLOCKED}s.net.in/cgi-bin/stringfile.php
  • http://kknk-shop.dev{BLOCKED}igital.com/stringfile.php
  • http://{BLOCKED}ersan.com.tr/wp-content/plugins/contact-form-maker/images/02/03/stringfile.php
  • http://{BLOCKED}ein-schubert.de/modules/mod_cmscore/stringfile.php