RANSOM_HIDDENTEARWUPDIS.A

June 22, 2017
 Analysis by: Cris Nowell Pantanilla
 ALIASES:

Ransom:Win32/FileCryptor (Microsoft)

 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 with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

15,872 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

15 Jun 2017

Payload:

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:

  • %Windows%\WinUpdatesDisabler.exe

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

It drops the following files:

  • C:\Key.txt

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
WinUpdatesDisabler = "%Windows%\WinUpdatesDisabler.exe"

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Speech\AppLexicons

HKEY_CURRENT_USER\Software\Microsoft\
Speech\PhoneConverters

HKEY_CURRENT_USER\Software\Microsoft\
Speech\CurrentUserLexicon

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .7z
  • .asp
  • .aspx
  • .avi
  • .bmp
  • .csv
  • .doc
  • .docx
  • .gif
  • .htm
  • .html
  • .jcf
  • .jgf
  • .jkm
  • .jpg
  • .jsb
  • .jsd
  • .jsh
  • .jsm
  • .jss
  • .mdb
  • .mp3
  • .odt
  • .php
  • .png
  • .ppt
  • .pptx
  • .psd
  • .rar
  • .sln
  • .sql
  • .txt
  • .wav
  • .wmv
  • .xls
  • .xlsx
  • .xml
  • .zip

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

  • {filename}.zbt

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

  • Payment information for decryption.txt

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

  • Ej sestrice, moraš da gi platiš.
    Ako gi ne platiš,
    zakljucani fajlovi,
    nema da gi vratiš

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.474.01

FIRST VSAPI PATTERN DATE:

15 Jun 2017

VSAPI OPR PATTERN File:

13.475.00

VSAPI OPR PATTERN Date:

16 Jun 2017

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

Delete this registry value

[ 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.

 
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • WinUpdatesDisabler = "%Windows%\WinUpdatesDisabler.exe""

Step 3

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.

  • In HKEY_CURRENT_USER\Software\Microsoft\Speech
    • AppLexicons
  • In HKEY_CURRENT_USER\Software\Microsoft\Speech
    • PhoneConverters
  • In HKEY_CURRENT_USER\Software\Microsoft\Speech
    • CurrentUserLexicon

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. Payment information for decryption.txt
C:\Key.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_HIDDENTEARWUPDIS.A. 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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