Ransom.Win32.HILDA.THIOFAIA

September 18, 2019
 Modified by: Henry Alarcon Jr.
 ALIASES:

RDN/Generic.dx (McAfee); HEUR:Trojan.MSIL.DelShad.gen (Kaspersky); Troj/Ransom-FPU (Sophos); Win32.Malware!Drop (Sunbelt)

 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:

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 encrypts files found in specific folders. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

266,752 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Sep 2019

Payload:

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 files:

  • %User Profile%\AppData\Roaming{00000000-0000-0000-0000-000000000000}\nflxcoreupdate_WOW64.exe ← detected as TROJ_GEN.R03BC0PI519
  • %User Profile%\AppData\Roaming{00000000-0000-0000-0000-000000000000}\HildaloliLOVESMHTandVK_Intel.exe ← normal file, Sysinternals Sdelete

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • "net.exe" /stop WinDefend /y
  • "net.exe" /stop MBAMService /y
  • "vssadmin.exe" Delete Shadows /All /Quiet
  • %System%\net1 /stop MBAMService /y
  • %System%\net1 /stop WinDefend /y

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

It creates the following folders:

  • %User Profile%\AppData\Roaming{00000000-0000-0000-0000-000000000000}

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • RstrMgr3887CAB8-533F-4C85-B0DC-3E5639F8D511
  • RstrMgr-3887CAB8-533F-4C85-B0DC-3E5639F8D511-Session0000

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • .3g2
  • .3gp
  • .7z
  • .accdb
  • .accde
  • .accdr
  • .accdt
  • .agdl
  • .ai
  • .asp
  • .aspx
  • .avi
  • .back
  • .backup
  • .backupdb
  • .bak
  • .bank
  • .blend
  • .c
  • .cdr3
  • .cdr4
  • .cdr5
  • .cdr6
  • .cdrw
  • .cer
  • .class
  • .cpp
  • .craw
  • .cs
  • .csv
  • .db
  • .dbf
  • .db-journal
  • .ddoc
  • .ddrw
  • .design
  • .djvu
  • .doc
  • .docm
  • .docx
  • .dotm
  • .dotx
  • .erbsql
  • .flac
  • .flv
  • .gray
  • .grey
  • .h
  • .htm
  • .html
  • .ibank
  • .incpas
  • .indd
  • .jar
  • .java
  • .jpeg
  • .jpg
  • .jsp
  • .kdbx
  • .key
  • .kpdx
  • .m4v
  • .mdb
  • .moneywell
  • .mov
  • .mp3
  • .mp4
  • .mpg
  • .ods
  • .odt
  • .pages
  • .pdf
  • .php
  • .php5
  • .phtml
  • .pl
  • .png
  • .potm
  • .potx
  • .ppam
  • .pps
  • .ppsm
  • .ppsx
  • .ppt
  • .pptm
  • .pptx
  • .ps
  • .psafe3
  • .psd
  • .pspimage
  • .py
  • .rar
  • .rm
  • .rtf
  • .s3db
  • .sas7bdat
  • .sldm
  • .sldx
  • .sql
  • .sqlite
  • .sqlite3
  • .sqlitedb
  • .svg
  • .swf
  • .tex
  • .tif
  • .txt
  • .vob
  • .wallet
  • .wav
  • .wmv
  • .wpd
  • .wps
  • .xlam
  • .xlr
  • .xlsb
  • .xlsm
  • .xlsx
  • .xltm
  • .xltx
  • .xml
  • .ycbcra
  • .zip

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

  • .HILDA!

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

  • {Encrypted File Directory}\READ_IT.TXT

It leaves text files that serve as ransom notes containing the following text:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.348.03

FIRST VSAPI PATTERN DATE:

06 Sep 2019

VSAPI OPR PATTERN File:

15.349.00

VSAPI OPR PATTERN Date:

07 Sep 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.XXPE50FFF031

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

Identify and terminate files detected as Ransom.Win32.HILDA.THIOFAIA

[ 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

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Profile%\AppData\Roaming{00000000-0000-0000-0000-000000000000}

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.
  • {Encrypted File Directory}\READ_IT.TXT

Step 6

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.HILDA.THIOFAIA. 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 7

Restore encrypted files from backup.


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