RANSOM_WNDIE.A

 Analysis by: Michael Jhon Ofiaza

 ALIASES:

Trojan.MSIL.DOTHETUK.ngf (Kaspersky) , Ransom.HiddenTear!g1 (Norton) , Ransom:Win32/Genasom (Microsoft)

 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:

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 adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

It encrypts files with specific file extensions.

  TECHNICAL DETAILS

File Size:

824,320 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

17 Nov 2017

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:

  • {malware path}\Proc.bat -used to grant the user access rights
  • {malware path}\@WannaDecrypt0r.png - used as wallpaper
  • {malware path}\a.wndi
  • {malware path}\t.wndi
  • {malware path}\d.wndi

It drops and executes the following files:

  • {malware path}\@WannaDecrypt0r.exe
  • {malware path}\Pros.vbs - executes proc.bat

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

  • wanadie

Autostart Technique

This Ransomware drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

  • %Start Menu%\Programs\Startup\ms.lnk

(Note: %Start Menu% is the Start Menu folder, where it usually is C:\Documents and Settings\{user name}\Start Menu on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other System Modifications

This Ransomware modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = 1

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = 0

It adds the following registry entries to disable the Task Manager:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = {malware path}\@WannaDecrypt0r.png

It sets the system's desktop wallpaper to the following image:

Other Details

This Ransomware does the following:

  • It sets the attribute of its initial copy to hidden
  • It displays a pop-up window with the following message:

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .dt
  • .1cd
  • .DT
  • .md
  • .dt
  • .hbk
  • .xltm
  • .xltx
  • .xlc
  • .xlm
  • .xlt
  • .hbk
  • .xlw
  • .xlsb
  • .xlsm
  • .xlsx
  • .xls
  • .html
  • .csv
  • .dat
  • .ged
  • .key
  • .keychain
  • .pps
  • .ppt
  • .pptx
  • .sdf
  • .tar
  • .tax2014
  • .tax2015
  • .vcf
  • .xml
  • .txt
  • .dotx

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

  • .wndie

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.794.04

FIRST VSAPI PATTERN DATE:

20 Nov 2017

VSAPI OPR PATTERN File:

13.795.00

VSAPI OPR PATTERN Date:

21 Nov 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

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_WNDIE.A

[ 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

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • From: DisableTaskMgr = 1
      To: DisableTaskMgr = 0

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.
  • {malware path}\Proc.bat  -used to grant the user access rights
  • {malware path}\@WannaDecrypt0r.png - used as wallpaper
  • {malware path}\a.wndi
  • {malware path}\t.wndi
  • {malware path}\d.wndi
  • {malware path}\@WannaDecrypt0r.exe
  • {malware path}\Pros.vbs - executes proc.bat
  • %Start Menu%\Programs\Startup\ms.lnk

Step 6

Scan your computer with your Trend Micro product to delete files detected as RANSOM_WNDIE.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 the following Trend Micro Support pages for more information:

Step 7

Restore encrypted files from backup.

Step 8

Reset your Desktop properties

[ Learn More ]


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