Analysis by: Jeanne Jocson
ALIASES:

Ransom.Locky (Symantec)

 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: Dropped by other malware, Downloaded from the Internet

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.

  TECHNICAL DETAILS

File Size: 137,591 bytes
File Type: DLL
Memory Resident: No
Initial Samples Received Date: 21 Nov 2016
Payload: Encrypts files, Connects to URLs/IPs, Displays images

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:

  • {folder of encrypted files}\_{count of folders where files are encrypted}-INSTRUCTION.html ← Ransom Note

It drops and executes the following files:

  • %Desktop%\-INSTRUCTION.html ← Ransom Note
  • %Desktop%\-INSTRUCTION.bmp ← Ransom Note, 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 modifies the following file(s):

  • It encrypts files in fixed, removable, RAM disk drives, and network shares.

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

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"

(Note: The default value data of the said registry entry is {user preference}.)

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

(Note: The default value data of the said registry entry is {user preference}.)

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Desktop%\-INSTRUCTION.bmp

(Note: The default value data of the said registry entry is {user preference}.)

Other Details

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

  • {BLOCKED}.{BLOCKED}.66.16/information.cgi
  • http://{Domain Generated Algorithm}.{edu, net, org, com}/information.cgi

It encrypts files with the following extensions:

  • .7zip
  • .SQLI
  • .accd
  • .agdl
  • .aiff
  • .aspx
  • .asse
  • .back
  • .bank
  • .blen
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .clas
  • .conf
  • .cont
  • .craw
  • .d3db
  • .db_j
  • .ddoc
  • .ddrw
  • .desi
  • .djvu
  • .docb
  • .docm
  • .docx
  • .dotm
  • .dotx
  • .erbs
  • .flac
  • .flvv
  • .forg
  • .gray
  • .grey
  • .grou
  • .html
  • .iban
  • .incp
  • .indd
  • .java
  • .jpeg
  • .kdbx
  • .kpdx
  • .lacc
  • .lay6
  • .lite
  • .m2ts
  • .mapi
  • .mone
  • .mpeg
  • .ms11
  • .nvra
  • .onet
  • .page
  • .plus
  • .potm
  • .potx
  • .ppam
  • .ppsm
  • .ppsx
  • .pptm
  • .pptx
  • .psaf
  • .pspi
  • .qcow
  • .s3db
  • .safe
  • .sas7
  • .save
  • .sldm
  • .sldx
  • .sqli
  • .tar.
  • .tiff
  • .vbox
  • .vhdx
  • .vmdk
  • .vmsd
  • .vmxf
  • .wall
  • .xlam
  • .xlsb
  • .xlsm
  • .xlsx
  • .xltm
  • .xltx
  • .ycbc

It renames encrypted files using the following names:

  • {first 8 hex characters of ID}-{next 4 hex characters of ID}-{last 4 hex characters of ID}-{4 hex characters}-{12 hex characters}.aesir

It does the following:

  • It requires a specific parameter in order to perform its intended routine:
    • "{Malware Path}\{Malware Filename}.dll",jWo7sg8u
  • It prevents encrypting files containing any of the strings in its full path name:
    • Winnt
    • Application Data
    • AppData
    • Program Files (x86)
    • Program Files
    • thumbs.db
    • $Recycle.Bin
    • System Volume Information
    • Windows
  • It deletes shadow copies by executing the following command:
    • vssadmin.exe Delete Shadows /Quiet /All

NOTES:

This ransomware changes the wallpaper with the following image:

It drops the following ransom note:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.912.06
FIRST VSAPI PATTERN DATE: 21 Nov 2016
VSAPI OPR PATTERN File: 12.913.00
VSAPI OPR PATTERN Date: 22 Nov 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

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

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these files

[ 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.
  • {folder of encrypted files}\_{count of folders where files are encrypted}-INSTRUCTION.html
  • %Desktop%\-INSTRUCTION.html
  • %Desktop%\-INSTRUCTION.bmp

Step 5

Reset your Desktop properties

[ Learn More ]

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_LOCKY.DLDTAQO. 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 7

Restore encrypted files from backup.

Step 8

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