Analysis by: Patrick Angelo Roderno
ALIASES:

DeepScan:Generic.Ransom.Saturn.9CF8214B (BITDEFENDER); Ransom-Saturn (NAI); Trojan:Win32/Occamy.B (MICROSOFT)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

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 itself after execution.

It encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 346,624 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 14 Feb 2018
Payload: Displays graphics/image, Encrypts files

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 processes:

  • vssadmin.exe delete shadows /all /quiet
  • wmic.exe shadowcopy delete
  • bcdedit /set {default} bootstatuspolicy ignoreallfailures
  • bcdedit /set {default} recoveryenabled no
  • wbadmin delete catalog -quiet
  • ping 1.1.1.1 -n 1 -w 3000 > Nul
  • Del "{Full Path of the Malware}\{Malware Name}.exe"
  • notepad.exe %Desktop%\#DECRYPT_MY_FILES#.txt
  • wscript.exe %Desktop%\#DECRYPT_MY_FILES#.vbs

(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.)

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

  • {Random 32-character string}

Autostart Technique

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

  • {Random characters}.lnk -> gets deleted after execution of the ransomware

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Saturn-{Mutex Name}

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Desktop%\#DECRYPT_MY_FILES.BMP

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

Dropping Routine

This Ransomware drops the following files:

  • {Folder of encrypted files}\#KEY-{Mutex Name}.KEY
  • %Desktop%\#DECRYPT_MY_FILES.BMP
  • %Desktop%\#DECRYPT_MY_FILES.vbs

(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 Details

This Ransomware deletes itself after execution.

It checks if the following virtual machine or sandbox related module(s) is loaded in the affected system:

  • Sbie.dll

It checks if the following virtual machine- or sandbox-related registry keys are present in the affected system:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\VBoxGuest

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\VBoxMouse

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\VBoxService

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\VBoxSF

HKEY_LOCAL_MACHINE\SOFTWARE\Oracle\
VirtualBox Guest Additions

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .123
  • .1cd
  • .3dm
  • .3ds
  • .602
  • .7z
  • .accdb
  • .aif
  • .apk
  • .asm
  • .asp
  • .avi
  • .backup
  • .bak
  • .bat
  • .bmp
  • .c
  • .cd
  • .cdr
  • .cfg
  • .cgm
  • .class
  • .com
  • .config
  • .cpp
  • .crt
  • .cs
  • .csr
  • .csv
  • .dat
  • .db
  • .dbf
  • .dif
  • .doc
  • .docm
  • .docp
  • .docx
  • .dwg
  • .gadget
  • .gif
  • .h
  • .ico
  • .iff
  • .jar
  • .java
  • .jpeg
  • .jpg
  • .js
  • .json
  • .lib
  • .m3u
  • .m4a
  • .max
  • .md
  • .mdb
  • .mid
  • .mov
  • .mp3
  • .mp4
  • .mpa
  • .ms11
  • .ms11 (Security copy)
  • .msg
  • .nef
  • .obj
  • .odg
  • .odt
  • .ogg
  • .p12
  • .pages
  • .pas
  • .pdb
  • .pdf
  • .pem
  • .php
  • .png
  • .pproj
  • .pps
  • .ppt
  • .pptm
  • .pptx
  • .prproj
  • .ps1
  • .psd
  • .py
  • .qcow2
  • .rar
  • .rtf
  • .sfk
  • .sql
  • .sqlite
  • .svg
  • .tar
  • .text
  • .tif
  • .tiff
  • .torrent
  • .txt
  • .vb
  • .vbox
  • .vbs
  • .vdi
  • .veg
  • .vmdk
  • .vmx
  • .wallet
  • .wav
  • .wma
  • .wmv
  • .wpd
  • .wps
  • .wsf
  • .xlm
  • .xls
  • .xlsb
  • .xlsm
  • .xlsx
  • .xml
  • .zip

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

  • .saturn
  • .nEcU0UXVhEua1FgY

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

  • \Program Files
  • Windows\
  • :\ProgramData\
  • AppData\Local\
  • AppData\LocalLow\
  • AppData\Roaming\Microsoft\
  • $Recycle Bin\
  • ApplicationData\
  • \Tor Browser\

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

  • .saturn

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

  • {Folder of encrypted files}\#DECRYPT_MY_FILES#.txt
  • {Folder of encrypted files}\#DECRYPT_MY_FILES#.html

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.988.04
FIRST VSAPI PATTERN DATE: 25 Feb 2018
VSAPI OPR PATTERN File: 13.989.00
VSAPI OPR PATTERN Date: 26 Feb 2018

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

Identify and terminate files detected as RANSOM_SATURN.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\Software
    • Saturn-{Mutex Name}

Step 5

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}\#DECRYPT_MY_FILES#.txt
  • {Folder of encrypted files}\#DECRYPT_MY_FILES#.html
  • {Folder of encrypted files}\#KEY-{Mutex Name}.KEY
  • %Start Menu%\Programs\Startup\{Random Characters}.lnk
  • %Desktop%\#DECRYPT_MY_FILES.BMP
  • %Desktop%\#DECRYPT_MY_FILES.vbs

Step 6

Scan your computer with your Trend Micro product to delete files detected as RANSOM_SATURN.A. 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 the following Trend Micro Support pages for more information:

Step 7

Reset your Desktop properties

[ Learn More ]

Step 8

Restore encrypted files from backup.

NOTES:

Clean Solution:

  1. Enable services disabled using the command prompt.
  2. Run cmd.exe as administrator.
  3. To enable Volume Shadow Service, use the following command:

    net start vss

  4. To enable Windows Error Recovery Screen on Startup, use the command:

    bcdedit /set {default} bootstatuspolicy displayallfailures

  5. To enable Startup Repair, use the command:

    bcedit /set {default} recoveryenabled Yes


Did this description help? Tell us how we did.