RANSOM_LOCKY.TIAOKAI

This ransomware is downloaded from Greenflash-Sundown exploit kit's use of CVE-2018-4878.

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 deletes the initially executed copy of itself.

It drops files as ransom note.

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 copies of itself into the affected system and executes them:

• %User Temp%\svchosta.exe (Windows Vista or above)
• %Application Data%\svchosta.exe (Windows XP or below)

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It drops the following files:

• %System Root%\Users\Public\PUBLIC (Windows Vista or above)
• %System Root%\Documents and Settings\Default User\PUBLIC (Windows XP or below)
• %System Root%\Users\Public\UNIQUE_ID_DO_NOT_REMOVE (Windows Vista or above)
• %System Root%\Documents and Settings\Default User\UNIQUE_ID_DO_NOT_REMOVE (Windows XP or below)

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It drops and executes the following files:

• %User Temp%\svchostaaexe.bat (Windows Vista or above) -> used to delete initial copy and itself
• %Application Data%\svchostaaexe.bat (Windows XP or below) -> used to delete initial copy and itself

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Autostart Technique

This Ransomware enables its automatic execution at every system startup by dropping the following copies of itself into the Windows Common Startup folder:

• %User Startup%\start.bat -> used to execute dropped copy

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows XP, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other Details

This Ransomware displays a pop-up window with the following message:

It does the following:

• It encrypts files on all drives except for the following:
  • CD-ROM drive

It deletes the initially executed copy of itself

Ransomware Routine

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

• DECRYPT_INFORMATION.html
• UNIQUE_ID_DO_NOT_REMOVE
• *exe
• *dll
• *lnk
• *ini
• *hrmlog

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

• Windows
• AhnLab
• Microsoft
• Chrome
• Mozilla
• $Recycle.Bin
• WINDOWS

It drops the following file(s) as ransom note:

• {Folder Containing Encrypted Files}\DECRYPT_INFORMATION.html

NOTES:

The Ransom note displays the following: