Ransom.BAT.CRYPENCODE.A

March 05, 2020
 Analysis by: Joshua Paul Ignacio
 ALIASES:

Trojan.BAT.Ransom (IKARUS), Trojan.BAT.36400 (QUICKHEAL)

 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 executes then deletes itself afterward.

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

  TECHNICAL DETAILS

File Size:

7,427,407 bytes

File Type:

BAT

Memory Resident:

No

Initial Samples Received Date:

24 Feb 2020

Payload:

Drops files, Displays message/message boxes

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:

  • %System Root%\x
  • %System Root%\krnln.fnr
  • %System Root%\CXK-NMSL-DATA.exe
  • %System Root%\x.js
  • %System Root%\x.vbs
  • %User Temp%\录娄脛茫脤芦脙脌.mp3
  • %Application Data%\wallpaper.jpg
  • %System Root%\z.zip

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It executes then deletes itself afterward.

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Application Data%\wallpaper.jpg

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

Other Details

This Ransomware displays the following message boxes:


It does the following:

  • It executes the following after encrypting the files:
    • %User Temp%\录娄脛茫脤芦脙脌.mp3

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

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %System Root%
  • %User Profile%
  • %User Profile%\Desktop
  • %User Profile%\Downloads
  • %User Profile%\Favorites
  • %User Profile%\Searches
  • %User Profile%\Saved Games
  • %User Profile%\Contacts
  • %User Profile%\Links
  • %User Profile%\Videos
  • %User Profile%\Pictures
  • %User Profile%\Documents
  • %User Profile%\Music

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %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 appends the following extension to the file name of the encrypted files:

  • .cxk_nmsl

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

  • {Encrypted Directory}\CXK-NMSL-README.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.704.04

FIRST VSAPI PATTERN DATE:

24 Feb 2020

VSAPI OPR PATTERN File:

15.705.00

VSAPI OPR PATTERN Date:

25 Feb 2020

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 these files

[ Learn More ]
There may be some component 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 Directory}\CXK-NMSL-README.txt
  • %System Root%\x
  • %System Root%\z.zip
  • %System Root%\krnln.fnr
  • %System Root%\CXK-NMSL-DATA.exe
  • %System Root%\x.js
  • %System Root%\x.vbs
  • %User Temp%\录娄脛茫脤芦脙脌.mp3
  • %Application Data%\wallpaper.jpg

Step 4

Scan your computer with your Trend Micro product to delete files detected as Ransom.BAT.CRYPENCODE.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 5

Reset your Desktop properties

[ Learn More ]

Step 6

Restore encrypted files from backup.


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