Analysis by: Alyssa Christelle Ramos
ALIASES:

a variant of Win32/Filecoder.Ragnarok.A trojan(NOD32);Trojan.Win32.DelShad.cha(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: 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: 215,040 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 05 Feb 2020
Payload: 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:

  • cmd.exe /c bcdedit /set {current} bootstatuspolicy ignoreallfailures
  • cmd.exe /c bcdedit /set {current} recoveryenabled no
  • cmd.exe /c netsh advfirewall set allprofiles state off ->Turns off Windows Firewall
  • cmd.exe /c vssadmin delete shadows /all /quiet -> Clear shadow volume copies

Other System Modifications

This Ransomware modifies the following registry entries to modify Group Policy Settings:

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

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

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

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

Other Details

This Ransomware does the following:

  • Checks installed Windows Language ID, if equal to the following and if it matches it will not perform its encryption:
    • 0419 = Russia
    • 0423 = Belarus
    • 0444 = Russia
    • 0442 = Turkmenistan
    • 0422 = Ukraine
    • 0426 = Latvia
    • 043f = Kazakhstan
    • 042c = Azerbaijan

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:

  • !!ReadMe_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: 15.676.03
FIRST VSAPI PATTERN DATE: 10 Feb 2020
VSAPI OPR PATTERN File: 15.677.00
VSAPI OPR PATTERN Date: 11 Feb 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

Restart in Safe Mode

[ Learn More ]

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out 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 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.
  • !!ReadMe_To_Decrypt_My_Files.txt

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.RAGNAROK.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 this Knowledge Base page for more information.

Step 7

Restore encrypted files from backup.

Step 8

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


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