Analysis by: Mc Justine De Guzman
ALIASES:

Trojan-Ransom.Win32.Crypren.ahel (KASPERSKY) ; W32/Crypren.AHEL!tr (FORTINET)

 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.

  TECHNICAL DETAILS

File Size: 78,336 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Aug 2020
Payload: Collects system information, Connects to URLs/IPs, Displays windows, 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.

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
WinWord64 = {Malware full path}

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows
Infected = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows
Ransom = 0

Information Theft

This Ransomware gathers the following data:

  • Computer Name
  • User Name
  • Number of infected files
  • Timestamp

Stolen Information

This Ransomware sends the gathered information via HTTP POST to the following URL:

  • hooks.{BLOCKED}k.com/services/TJJ5KPZ7Y/{BLOCKED}NSW/QkZIsP8K9rOfWVCuJEzgf9Pv

Other Details

This Ransomware encrypts files with the following extensions:

  • .bmp
  • .jpg
  • .jpeg
  • .png
  • .gif
  • .mp4
  • .mpg
  • .mpeg
  • .mov
  • .mkv
  • .m2ts
  • .mp3
  • .m4a
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .pdf
  • .txt

It does the following:

  • It shows the following dialog box as ransom note:

It does not proceed to its malicious routine if it detects that it is being debugged.

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .encrypted

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 16.226.06
FIRST VSAPI PATTERN DATE: 14 Sep 2020
VSAPI OPR PATTERN File: 16.227.00
VSAPI OPR PATTERN Date: 15 Sep 2020

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.Win32.TRX.XXPE50FFF036

Step 2

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 3

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 4

Restart in Safe Mode

[ Learn More ]

Step 5

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
    • WinWord64 = {Malware full path}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • Infected = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • Ransom = 0

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.CRYPREN.C. 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 7

Restore encrypted files from backup.


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