RANSOM.MSIL.SHRUG.THGACAH

October 15, 2018
 Analysis by: Patrick Angelo Roderno
 ALIASES:

Trojan-Ransom.MSIL.Agent.fqnc (KASPERSKY); Gen:Variant.Ransom.685 (NORTON); RDN/Generic Dropper (NAI)

 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 connects to certain websites to send and receive information.

It encrypts files with specific file extensions. It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

25088 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

30 Jun 2018

Payload:

Drops files, Steals information, Collects system information, Connects to URLs/IPs, Modifies system registry, Deletes files, Blocks user desktop, Disables services

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.

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Shrug
installdate = {Date of infection}

HKEY_CURRENT_USER\Shrug
identifier = {User Name}/{Machine Name}

HKEY_CURRENT_USER\Shrug
installed = true

HKEY_CURRENT_USER\Shrug
key = {key used in encryption}

HKEY_CURRENT_USER\Shrug
iv = {initialization vector used in encryption}

Information Theft

This Ransomware gathers the following data:

  • Current Date
  • User Name
  • Computer Name

Other Details

This Ransomware connects to the following URL(s) to check for an Internet connection:

  • http://{BLOCKED}s3.{BLOCKED}e.com/generate_204

It connects to the following website to send and receive information:

  • http://{BLOCKED}c11vl.{BLOCKED}pp.com/{BLOCKED}ff/uploadhash.php

It does the following:

  • It monitors keyboard events and prevents the following combination of keyboard keys to perform its intended events:
    • Windows Key
    • Alt+Tab
    • Ctrl+ESC
    • Ctrl+Alt+Delete
    • Shift+Esc
    • Ctrl+W
    • Alt+F4
  • Disables keyboard and mouse events from reaching applications
  • Deletes encrypted files after three days if the victim does not pay the ransom
  • Locks the victim's screen and displays the following:

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .asp
  • .aspx
  • .avi
  • .c
  • .cpp
  • .cs
  • .csv
  • .dat
  • .db
  • .doc
  • .docx
  • .gif
  • .html
  • .html
  • .java
  • .jpeg
  • .jpg
  • .js
  • .json
  • .mdb
  • .mp3
  • .mp4
  • .mpeg
  • .msi
  • .odt
  • .ogg
  • .php
  • .png
  • .ppt
  • .pptx
  • .psd
  • .py
  • .pyw
  • .sln
  • .sql
  • .txt
  • .wmv
  • .xls
  • .xlsx
  • .xml

It encrypts files found in the following folders:

  • C:\

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

  • .SHRUG

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.376.02

FIRST VSAPI PATTERN DATE:

13 Jul 2018

VSAPI OPR PATTERN File:

14.377.00

VSAPI OPR PATTERN Date:

14 Jul 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 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

Identify and terminate files detected as RANSOM.MSIL.SHRUG.THGACAH

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • HKEY_CURRENT_USER\Shrug

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM.MSIL.SHRUG.THGACAH. 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 6

Restore encrypted files from backup.


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