Ransom.Win32.STOP.THDOEBD

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.

As of this writing, the said sites are inaccessible.

It drops files as ransom note. It avoids encrypting files with the following file extensions.

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 adds the following folders:

• %AppDataLocal%\{UUID 1}
• %AppDataLocal%\{UUID 2}
• %System Root%\SystemID

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It drops the following copies of itself into the affected system:

• %AppDataLocal%\{UUID 1}\{Malware Name}

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following files:

• %User Temp%\delself.bat ← deletes the malware if it is found to be executing on a system that is located in particular countries
• %System%\Tasks\Time Trigger Task ← creates scheduled task for the malware
• %AppDataLocal%\bowsakkdestx.txt ← contains the public key and system encryption identifier, deleted afterwards
• %System Root%\SystemID\PersonalID.txt ← unique identifier for the affected system

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It adds the following processes:

• {Malware File Path}\{Malware Name} "{Malware File Path}\{Malware Name}"
• icacls "%AppDataLocal%\{UUID 1}" /deny *S-1-1-0:(OI)(CI)(DE,DC) ← protect this path/folder
• {Malware File Path}\{Malware Name} --Admin IsNotAutoStart IsNotTask

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• {1D6FC66E-D1F3-422C-8A53-C0BBCF3D900D}
• {FBB4BCC6-05C7-4ADD-B67B-A98A697323C1}
• IESQMMUTEX_0_208

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
SysHelper = %AppDataLocal%\{UUID 1}\{Malware File Name} --AutoStart

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
SysHelper = 1

Backdoor Routine

This Ransomware connects to the following URL(s) to send and receive commands from a remote malicious user:

• http://{BLOCKED}q.com/test1/get.php?pid={MAC ADDRESS HASH} ← used to receive public key and system encryption identifier for the affected system.

Download Routine

This Ransomware connects to the following website(s) to download and execute a malicious file:

• http://{BLOCKED}q.com/files/1/build3.exe
• http://{BLOCKED}my.com/dl/build2.exe

As of this writing, the said sites are inaccessible.

Information Theft

This Ransomware gathers the following data:

• IP Address
• MAC Address
• Computer Name
• User Name

Other Details

This Ransomware connects to the following URL(s) to get the affected system's IP address:

• https://{{BLOCKED}p.ua/geo.json -->
  • It terminates and deletes itself on the affected system if the return of the IP address location is any of the following:
  • RU (Russia)
  • BY (Belarus)
  • UA (Ukraine)
  • AZ (Azerbaijan)
  • AM (Armenia)
  • TJ (Tajikistan)
  • KZ (Kazakhstan)
  • KG (Kyrgyzstan)
  • UZ (Uzbekistan)
  • SY (Syrian Arab Republic)

It does the following:

• It checks if it is running on Windows XP or lower Windows versions. If this condition is met, it will check for a service named "MYSQL" and terminate it.
• It tries to open the following file(s):
  • I:\5d2860c89d774.jpg

It accepts the following parameters:

• --Admin → the malware is executed with admin privileges
• --AutoStart → the malware is executed using autorun registry key(s)
• --Task → the malware is executed using the created scheduled task
• IsAutoStart/IsNotAutoStart → executes malware as an autostart or not
• IsTask/IsNotTask → executes malware as a scheduled task or not

It adds the following scheduled tasks:

• Task Name: Azure-Update-Task
  Task Action: %Application Data%\Microsoft\Network\mstsca.exe
• Task Name: Time Trigger Task
  Task Action: %AppDataLocal\{Malware Name} --Task

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Ransomware Routine

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

• ntuser.dat
• ntuser.dat.LOG1
• ntuser.dat.LOG2
• ntuser.pol
• _readme.txt

It avoids encrypting files found in the following folders:

• %Program Files%\Google
• %Program Files%\Internet Explorer
• %Program Files%\Mozilla Firefox
• %System Root%\dell
• %System Root%\Games
• %System Root%\Intel
• %System Root%\MSOCache
• %System Root%\PerfLogs
• %System Root%\ProgramData
• %System Root%\Recovery
• %System Root%\SystemID
• %System Root%\Windows
• %System Root%\Windows.old
• {Drive Letter}\dell
• {Drive Letter}\Games
• {Drive Letter}\Intel
• {Drive Letter}\MSOCache
• {Drive Letter}\PerfLogs
• {Drive Letter}\Windows

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

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

• .xaro

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

• {Encrypted Directory}\_readme.txt
  

It avoids encrypting files with the following file extensions:

• .ini
• .DLL
• .dll
• .blf
• .bat
• .lnk
• .regtrans-ms