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Ransom.Win32.RYUK.WLDE

October 29, 2020
 Analysis by: Karen Ivy Titiwa
 ALIASES:

Trojan-Ransom.Ryuk(IKARUS)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • 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:

128,512 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Sep 2020

Payload:

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 drops the following copies of itself into the affected system and executes them:

  • {Malware Directory}\{9 random characters}lan.exe → 3 copies with different random characters

It adds the following processes:

  • icacls "{Drive Letter}:\*" /grant Everyone:F /T /C /Q → grants all users access to files and folders on the specified drive
  • net stop {Service Name} /y
  • taskkill /IM /F {Process Name}

Process Termination

This Ransomware terminates the following services if found on the affected system:

  • vmcomp
  • vmwp
  • veeam
  • Back
  • xchange
  • ackup
  • acronis
  • sql
  • Enterprise
  • Sophos
  • Veeam
  • AcrSch
  • Antivirus
  • bedbg
  • DCAgent
  • EPSecurity
  • EPUpdate
  • Eraser
  • EsgSh
  • Kernel
  • FA_Scheduler
  • IISAdmin
  • IMAP4
  • MBAM
  • Endpoint
  • Afee
  • McShield
  • task
  • mfemms
  • mfevtp
  • mms
  • MsDts
  • Exchange
  • ntrt
  • PDVF
  • POP3
  • Report
  • RESvc
  • sacsvr
  • SAVAdmin
  • SamS
  • SDRSVC
  • SepMaster
  • Monitor
  • Smcinst
  • Smc
  • Service
  • SMTP
  • SNAC
  • swi_
  • CCSF
  • TrueKey
  • tmlisten
  • UI0Detect
  • W3S
  • WRSVC
  • NetMsmq
  • ekrn
  • EhttpSrv
  • ESHASRV
  • AVP
  • klnagent
  • wbengine
  • KAVF
  • mfefire

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

  • virtual
  • vmcomp
  • vmwp
  • veeam
  • backup
  • Backup
  • xchange
  • sql
  • dbeng
  • sofos
  • calc
  • ekrn
  • zoolz
  • encsvc
  • excel
  • firefoxconfig
  • infopath
  • msaccess
  • mspub
  • mydesktop
  • ocautoupds
  • ocomm
  • ocssd
  • onenote
  • oracle
  • outlook
  • powerpnt
  • sqbcoreservice
  • steam
  • synctime
  • tbirdconfig
  • thebat
  • thunderbird
  • visio
  • word
  • xfssvccon
  • tmlisten
  • PccNTMon
  • CNTAoSMgr
  • Ntrtscan
  • mbamtray

Other Details

This Ransomware does the following:

  • It executes its 3 dropped copies with the following parameters:
    • "{Malware Directory}\{9 random characters}lan.exe" 8 LAN → attempts to turn on devices in the network using Wake-on-Lan feature. If successful, it will encrypt the files in device's administrative share.

Ransomware Routine

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

  • ntldr
  • bootmgr
  • NTDETECT
  • boot

It avoids encrypting files found in the following folders:

  • \Windows\
  • Windows
  • boot
  • WINDOWS
  • Chrome
  • Mozilla
  • SYSVOL
  • NTDS
  • netlogon
  • sysvol

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

  • .RYK

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

  • %User Temp%\RyukReadMe.html
  • {Encrypted Directory}\RyukReadMe.html
  • %Public%\RyukReadMe.html

It avoids encrypting files with the following file extensions:

  • .dll
  • .exe
  • .ini
  • .lnk

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

16.252.06

FIRST VSAPI PATTERN DATE:

27 Sep 2020

VSAPI OPR PATTERN File:

16.253.00

VSAPI OPR PATTERN Date:

28 Sep 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

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.  
  • {Malware Directory}\{9 random characters}lan.exe
  • {Malware Directory}\{9 random characters}lan.exe
  • {Malware Directory}\{9 random characters}lan.exe
  • %User Temp%\RyukReadMe.html
  • {Encrypted Directory}\RyukReadMe.html
  • %Public%\RyukReadMe.html

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.RYUK.WLDE. 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 6

Restore encrypted files from backup.


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