Ransom.Win32.RYUK.SMTH

April 18, 2019
 Analysis by: Maureen Reyes
 ALIASES:

Ransom:Win32/Jabaxsta.D!bit (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 executes then deletes itself afterward.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Initial Samples Received Date:

02 Apr 2019

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%\{Random}.exe
  • %Public%\sys

(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.)

It adds the following processes:

  • "%System%\net.exe" stop "audioendpointbuilder" /y
  • "%System%\net.exe" stop "samss" /y
  • "%System%\net.exe" stop "ui0detect" /y

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

It executes then deletes itself afterward.

Ransomware Routine

This Ransomware drops the following file(s) as ransom note:

  • {Encrypted Directory}:\RyukReadMe.txt
    or
    {Encrypted Directory}:\RyukReadMe.html

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.870.08

FIRST VSAPI PATTERN DATE:

14 Mar 2019

VSAPI OPR PATTERN File:

14.871.00

VSAPI OPR PATTERN Date:

15 Mar 2019

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

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.
  • %Public%\{Random}.exe
  • %Public%\sys
  • {Encrypted Directory}:\RyukReadMe.txt
  • {Encrypted Directory}:\RyukReadMe.html

Step 4

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.RYUK.SMTH. 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 5

Restore encrypted files from backup.


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