Analysis by: Neljorn Nathaniel Aguas

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

  TECHNICAL DETAILS

File Size: 14,893 bytes
File Type: PS1
Memory Resident: No
Initial Samples Received Date: 07 Mar 2024
Payload: Drops files, 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.

Dropping Routine

This Ransomware drops the following files:

  • {Malware Path}\Vulpixlist.txt → contains a text of the path of the ransom note

Other Details

This Ransomware does the following:

  • It avoids encrypting files with attributes set to HIDDEN.
  • It overwrites the content of the target files using the following format:
    • {Encrypted Data}{"ASTRID"}{Encryption Key Length}{Encryption IV Length}{Encryption Key}{Encryption IV}
  • It displays a fixed window while encrypting files:

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .doc
  • .docx
  • .jpeg
  • .pdf
  • .sql
  • .xls
  • .xlsx

It encrypts files found in the following folders:

  • C:\Adata → including subfolders

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

  • .vulpix

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

  • C:\Adata\VulpixReadMe.txt

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.272.04
FIRST VSAPI PATTERN DATE: 11 Apr 2024
VSAPI OPR PATTERN File: 19.273.00
VSAPI OPR PATTERN Date: 12 Apr 2024

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 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.  
  • C:\Adata\VulpixReadMe.txt
  • {Malware Path}\Vulpixlist.txt

Step 4

Scan your computer with your Trend Micro product to delete files detected as Ransom.PS1.VULPIX.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

Restore encrypted files from backup.


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