RANSOM_LOCKY.FU

June 03, 2016
 Analysis by: Rhena Inocencio
 ALIASES:

Ransom:Win32/Locky.A (Microsoft), Trojan-Ransom.Win32.Locky.aex (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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

195,886 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

03 Jun 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.

Other System Modifications

This Trojan modifies the following file(s):

  • It encrypts files and appends the extension .locky

It modifies the following registry entries:

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

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"

(Note: The default value data of the said registry entry is 2.)

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

(Note: The default value data of the said registry entry is 0.)

Dropping Routine

This Trojan drops the following files:

  • %Desktop%\_HELP_instructions.html
  • %Desktop%\_HELP_instructions.bmp

(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 Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.69.90/upload/_dispatch.php
  • http://{BLOCKED}.{BLOCKED}.123.60/upload/_dispatch.php
  • {pseudorandom domain}.{ru, info, biz, work, pl ,org, pw, xyz, click, su}

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.560.06

FIRST VSAPI PATTERN DATE:

31 May 2016

VSAPI OPR PATTERN File:

12.561.00

VSAPI OPR PATTERN Date:

01 Jun 2016

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

Search and delete these components

[ Learn More ]
There may be some components 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%\_HELP_instructions.html
  • %Desktop%\_HELP_instructions.bmp

Step 3

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

Step 4

Reset your Desktop properties

[ Learn More ]

Step 5

Restore encrypted files from backup.


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