RANSOM_RANDOMLOCK.THDCOAH

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It downloads a file from a certain URL then renames it before storing it in the affected system.

It connects to certain websites to send and receive information.

It encrypts files with specific file extensions. It encrypts files found in specific folders.

Arrival Details

This Ransomware 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 Ransomware drops the following files:

• {malware path}\wallpaper.png
• %User Profile%\Pictures\wallpaper.png -> used as desktop wallpaper

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Profile%\Pictures\wallpaper.png

It sets the system's desktop wallpaper to the following image:

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

• chrome
• firefox
• iexplore
• taskmgr
• cmd
• Powershell

Download Routine

This Ransomware downloads files from the following URLs then renames them before storage in the affected system:

• https://i.{BLOCKED}r.com/L2g45Xs.png

It saves the files it downloads using the following names:

• {malware path}\wallpaper.png

Other Details

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

• http://{BLOCKED}.{BLOCKED}.88.116/3DWYMbC9s3GMj7fj/adduser.php?id={username}{user domain name}&pass={key}

Ransomware Routine

This Ransomware encrypts files with the following extensions:

• .bat
• .hlp
• .xml
• .chm
• .ini
• .xls
• .xlsx
• .txt
• .exe
• .png
• .jpg
• .gif
• .bmp
• .pdf
• .doc
• .jpeg
• .dll
• .docx
• .rar
• .zip
• .html
• .php
• .mp3
• .mp4
• .wav
• .wmv

It encrypts files found in the following folders:

• %Desktop%
• %User Profile%\Documents
• %User Profile%\Pictures
• C:\Users\{Username}\Downloads
• C:\Users\Public

(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.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It avoids encrypting files with the following strings in their file name:

• {malware name}
• wallpaper.png

It appends the following extension to the file name of the encrypted files:

• .rand

NOTES:

This ransomware displays the following before encrypting files:

It also displays the following after encrypting files: