Analysis by: Robert Tacbad
ALIASES:

Ransom:Win32/Locky (Microsoft), Ransom.Locky (Malwarebytes)

 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.

It connects to certain websites to send and receive information. It deletes the initially executed copy of itself. It is capable of encrypting files in the affected system.

  TECHNICAL DETAILS

Tamaño del archivo 151,552 bytes
Tipo de archivo EXE
Residente en memoria No
Fecha de recepción de las muestras iniciales 09 Sep 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 files:

  • {folders containing encrypted files}\_{count of dropped note per folder}_HELP_instructions.html - ransom note

It drops and executes the following files:

  • %Desktop%\_HELP_instructions.html - ransom note
  • %Desktop%\_HELP_instructions.bmp - image used as wallpaper

(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.)

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Desktop%\_HELP_instructions.bmp

Other Details

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

  • http://{Domain}/data/info.php
    where {Domain} can be any of the following:
    • {BLOCKED}.{BLOCKED}.6.109
    • (BLOCKED}.{BLOCKED}.8.101
    • {BLOCKED}.{BLOCKED}.119.71
    • {Domain Generated Algorithm}.{ru, info, biz, click, su, work, pl, org, pw, xyz}

It renames encrypted files using the following names:

  • {unique ID per victim}-{identifier}.zepto

It deletes the initially executed copy of itself

It is capable of encrypting files in the affected system.

  SOLUTION

Motor de exploración mínimo 9.800
Primer archivo de patrones de VSAPI 12.772.02
Primera fecha de publicación de patrones de VSAPI 12 Sep 2016
Versión de patrones OPR de VSAPI 12.773.00
Fecha de publicación de patrones OPR de VSAPI 13 Sep 2016

NOTES:

Trend customers:

    Keep your pattern and scan engine files updated. Trend Micro antivirus software can clean or remove most types of computer threats. Malware, though, such as Trojans, scripts, overwriting viruses and joke programs which are identified as uncleanable, should simply be deleted.

All Internet users:

  • Use HouseCall - the Trend Micro online threat scanner to check for malware that may already be on your PC.
  • Catch malware/grayware before they affect your PC or network. Secure your Web world with Trend Micro products that offer the best anti-threat and content security solutions for home users, corporate users, and ISPs. Go here for more information on Trend Micro products that fit your needs.


Did this description help? Tell us how we did.