Ransom.Win32.RYUK.HUG

December 07, 2019
 Analysis by: Henry Alarcon Jr.
 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, Dropped by other malware

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:

619,176 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Dec 2019

Payload:

Collects system information, Drops files, 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:

  • {malware path}\{random}.exe

It drops the following files:

  • %System Root%\Document and Settings\Default User\window.bat -> deletes shadow copies and backup
  • %User Startup%\start.bat -> deletes shadow copies, backup
  • %User Startup%\RyukReadMe.html -> ransom notes
  • %Common Startup%\start.bat -> deletes shadow copies, backup

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).. %Common Startup% is the startup folder for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other Details

This Ransomware does the following:

  • It executes its copy having the following parameters:
    • {malware path}\{random}.exe 8 LAN
  • It searches for the following string in the machine's services. If the string is present in the service name, it will terminate the service by the following command "net stop "{service name}" /y":
    • 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
    • bootmgr
  • It terminates processes having the following strings, it uses "taskkill /IM /F {Process Name}" to terminate:
    • 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
    • veeam
  • Injects to all running processes except for the following:
    • explorer.exe
    • csrss.exe
    • lsaas.exe
    • {Malware Filename}.exe
  • The ransomware locks the machine once done encrypting.

Rogue Antivirus Routine

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

  • RyukReadMe.html
  • UNIQUE_ID_DO_NOT_REMOVE
  • PUBLIC
  • sysvol
  • netlogon
  • PRIVATE

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

  • \Windows\
  • AhnLab
  • Chrome
  • Mozilla
  • $Recycle.Bin
  • WINDOWS

It 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

It avoids encrypting files with the following file extensions:

  • .dll
  • .exe
  • .ini
  • .lnk
  • hrmlog

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.542.04

FIRST VSAPI PATTERN DATE:

06 Dec 2019

VSAPI OPR PATTERN File:

15.543.00

VSAPI OPR PATTERN Date:

07 Dec 2019

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.Win32.TRX.XXPE50FFF033

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

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 4

Restart in Safe Mode

[ Learn More ]

Step 5

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.
  • %System Root%\Document and Settings\Default User\window.bat
  • %Common Startup%\start.bat
  • %User Startup%\start.bat
  • %User Startup%\RyukReadMe.html
  • {Encrypted Directory}\RyukReadMe.html

Step 6

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