Analysis by: Bren Matthew Ebriega
ALIASES:

Ransom:Win32/RagnarLocker.DH!MTB (MICROSOFT); Trojan.Win32.DelShad.dbn (KASPERSKY)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

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

  TECHNICAL DETAILS

File Size: 216,576 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 29 Apr 2020
Payload: Modifies system registry, Terminates processes, Displays message/message boxes, 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:

  • %System%\cmd.exe /c vssadmin delete shadows /all /quiet → Clear Shadow Volume Copies
  • %System%\cmd.exe /c bcdedit /set {current} bootstatuspolicy ignoreallfailures
  • %System%\cmd.exe /c bcdedit /set {current} recoveryenabled no
  • %System%\cmd.exe /c netsh advfirewall set allprofiles state off → Turn off Windows Firewall

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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

  • name

Other System Modifications

This Ransomware modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiSpyware = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableRealtimeMonitoring = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableBehaviorMonitoring = 1

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableOnAccessProtection = 1

Process Termination

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

  • Process Names containing the following strings:
    • sql
    • note
    • powerpnt
    • winword
    • excel

Other Details

This Ransomware does the following:

  • Checks the installed Windows Language ID, if equal to the following and if it matches it will not perform its encryption:
    • 040a = Spanish - Spain (Traditional)
    • 040d = Hebrew
    • 0419 = Russian
    • 0422 = Ukrainian
    • 0423 = Belarusian
    • 0428 = Tajik
    • 042b = Armenian
    • 042c = Azeri - Latin
    • 043f = Kazakh
    • 0440 = Kyrgyz - Cyrillic
    • 0442 = Turkmen
    • 0443 = Uzbek - Latin
    • 0451 = Tibetan
    • 0478 = Yi
    • 0480 = Uighur - China
    • 0804 = Chinese - China
    • 0819 = Russian - Moldova
    • 082c = Azeri - Cyrillic

Ransomware Routine

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

  • content.ie5
  • \temporary internet files
  • \local settings\temp
  • \appdata\local\temp
  • \program files
  • \windows
  • \programdata
  • $

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

  • .ragnarok

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

  • {Encrypted Folder}\How_To_Decrypt_My_Files.txt

It avoids encrypting files with the following file extensions:

  • .exe
  • .dll
  • .sys
  • .ragnarok

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.868.04
FIRST VSAPI PATTERN DATE: 14 May 2020
VSAPI OPR PATTERN File: 15.869.00
VSAPI OPR PATTERN Date: 15 May 2020

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

Restore this modified registry value

[ 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_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
    • DisableAntiSpyware = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableRealtimeMonitoring = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableBehaviorMonitoring = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableOnAccessProtection = 1

Step 4

Search and delete this file

[ 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.  
  • {Encrypted Folder}\How_To_Decrypt_My_Files.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.RAGNAROK.B. 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 6

Restore encrypted files from backup.


Did this description help? Tell us how we did.