Ransom.MSIL.SYRK.A

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

• C:\Users\Default\AppData\Local\Microsoft\-pw+.txt -> contains password
• C:\Users\Default\AppData\Local\Microsoft\+dp-.txt -> contains password and victim ID
• C:\Users\Default\AppData\Local\Microsoft\-i+.txt -> contains victim ID

It drops and executes the following files:

• C:\Users\Public\Documents\cgo46ea565sdfse7.exe -> detected as Ransom.Win32.SYRK.A
  • used by the malware to search and encrypt files by executing a Powershell script
• C:\Users\Public\Documents\dh35s3h8d69s3b1k.exe -> detected as Trojan.Win32.SYRK.A
  • used in decrypting files, also uses a Powershell script
• C:\Users\Public\Documents\startSF.exe -> detected as Trojan.Win32.SYRK.A
  • used to move C:\Users\Public\Documents\SydneyFortniteHacks.exe to %User Startup%\SydneyFortniteHacks.exe
• C:\Users\Public\Documents\DeleteFile.exe -> detected as Trojan.Win32.SYRK.A
  • used to delete files this malware created
• C:\Users\Public\Documents\delmy.exe -> detected as Trojan.Win32.SYRK.A
  • used to delete the file: %User Startup%\SydneyFortniteHacks.exe
• C:\Users\Public\Documents\LimeUSB_Csharp.exe -> detected as Worm.MSIL.LIME.AA

Autostart Technique

This Ransomware drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

• %User Startup%\SydneyFortniteHacks.exe

(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 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

Other System Modifications

This Ransomware modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiSpyware = 0

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = 0

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

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 1

(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}.)

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

• C:\51875.jpg

Process Termination

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

• Taskmgr
• Procmon64
• ProcessHacker

Other Details

This Ransomware displays the following images:

• Main display:
  • 
• "Show My ID" button:
  • 
• If password input is correct and "Decrypt my Files" button is clicked:
  • 

It does the following:

• If the timer in the main display times out, it will delete files with .Syrk extension in the following directories:
  • %User Profile%\Desktop
  • %User Profile%\Document
  • %User Profile%\Pictures
• It pings the following URL:
  • {BLOCKED}94fg5sb3y8l.{BLOCKED}hostapp.com
• On execution, it will move {current directory}\SydneyFortniteHacks.exe to C:\Users\Public\Documents\SydneyFortniteHacks.exe
• It sends the following via SMTP:
  • Content:
    • Attachment: C:\Users\Default\AppData\Local\Microsoft\+dp-.txt
    • Subject: ID&Pass
  • To:
    • Host: {BLOCKED}mail.com
    • Email: {BLOCKED}som@gmail.com
• It has a built in decryptor but it will only work if the input password is correct.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

• gif
• sln
• docx
• php
• psd
• ico
• mov
• xlsx
• jpg
• xls
• doc
• pdf
• wav
• pptx
• ppt
• txt
• png
• bmp
• rar
• zip
• mp3
• mp4
• avi

It encrypts files found in the following folders:

• %User Profile%

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

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

• .Syrk

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

• %Desktop%\Readme_now.txt

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

It leaves text files that serve as ransom notes containing the following text: