Ransom.Win32.XORIST.AA

 Analysis by: Jay Bradley Nebre

 ALIASES:

Trojan-Ransom.Win32.Xorist.ln(Kaspersky); Trojan-Ransom.Xorist(Ikarus)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • 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 encrypts files with specific file extensions.

  TECHNICAL DETAILS

File Size:

25,088 bytes

File Compression:

UPX

Memory Resident:

Yes

Initial Samples Received Date:

17 Jun 2019

Payload:

Encrypts 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 a copy of itself in the following folders using different file names:

  • %User Temp%\4X37K2N6BbiJe52.exe

(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).)

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Alcmeter = %User Temp%\4X37K2N6BbiJe52.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.EnCiPhErEd

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
VISAMNYAEAAZCVJ

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
VISAMNYAEAAZCVJ\DefaultIcon

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
VISAMNYAEAAZCVJ\shell\open\
command

Other Details

This Ransomware displays the following message boxes:


Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .zip
  • .rar
  • .7z
  • .tar
  • .gzip
  • .jpg
  • .jpeg
  • .psd
  • .cdr
  • .dwg
  • .max
  • .bmp
  • .gif
  • .png
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .txt
  • .pdf
  • .djvu
  • .htm
  • .html
  • .mdb
  • .cer
  • .p12
  • .pfx
  • .kwm
  • .pwm
  • .1cd
  • .md
  • .mdf
  • .dbf
  • .odt
  • .vob
  • .ifo
  • .lnk
  • .torrent
  • .mov
  • .m2v
  • .3gp
  • .mpeg
  • .mpg
  • .flv
  • .avi
  • .mp4
  • .wmv
  • .divx
  • .mkv
  • .mp3
  • .wav
  • .flac
  • .ape
  • .wma
  • .ac3

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

  • .EnCiPhErEd

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

  • HOW TO DECRYPT FILES.txt

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.180.03

FIRST VSAPI PATTERN DATE:

17 Jun 2019

VSAPI OPR PATTERN File:

15.181.00

VSAPI OPR PATTERN Date:

18 Jun 2019

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

Identify and terminate files detected as Ransom.Win32.XORIST.AA

[ 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 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Alcmeter = %User Temp%\4X37K2N6BbiJe52.exe;
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.EnCiPhErEd
    • {default} = VISAMNYAEAAZCVJ;
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\VISAMNYAEAAZCVJ
    • {default} = CRYPTED!
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\VISAMNYAEAAZCVJ\DefaultIcon
    • {default} = %User Temp%\4X37K2N6BbiJe52.exe,0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\VISAMNYAEAAZCVJ\shell\open\command
    • {default} = %User Temp%\4X37K2N6BbiJe52.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.XORIST.AA. 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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