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Ransom.Win32.RYUK.THGOEAI

July 31, 2019
 Analysis by: Earle Maui Earnshaw
 ALIASES:

Ransom:Win64/Ryuk.PA!MTB (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 drops files as ransom note.

  TECHNICAL DETAILS

File Size:

168,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Jul 2019

Payload:

Terminates processes, 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 drops the following files:

  • %Public%\sys
  • %Public%\PUBLIC
  • %Public%\UNIQUE_ID_DO_NOT_REMOVE

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

Process Termination

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

  • back
  • xchange
  • ackup
  • acronis
  • sql
  • enterprise
  • sophos
  • veeam
  • acrsch
  • antivirus
  • bedbg
  • dcagent
  • epsecurity
  • epupdate
  • eraser
  • esgshkernel
  • 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
  • smcservice
  • 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:

  • 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

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .RYK

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

  • {Encrypted Directory}\RyukReadMe.html

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.216.02

FIRST VSAPI PATTERN DATE:

05 Jul 2019

VSAPI OPR PATTERN File:

15.217.00

VSAPI OPR PATTERN Date:

06 Jul 2019

Step 1

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 2

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 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.
  • %System Root%\users\Public\sys
  • %System Root%\users\Public\PUBLIC
  • %System Root%\users\Public\UNIQUE_ID_DO_NOT_REMOVE

Step 5

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