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Ransom.MSIL.CYPREN.A

April 18, 2023
 Analysis by: Rojan Dela Cruz
 ALIASES:

IL:Trojan.MSILZilla.25863 (BITDEFENDER), Ransom:MSIL/Cryptolocker.PDH!MTB (MICROSOFT)

 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:

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 found in specific folders. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

1,359,872 bytes

File Type:

, EXE

Memory Resident:

No

Payload:

Encrypts files, Displays graphics/image

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.

Other Details

This Ransomware does the following:

  • After a successful encryption routine, it will display the following images:

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %Desktop%
  • %User Profile%\Pictures
  • %User Profile%\Documents

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

  • .jcrypt

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

  • %Desktop%\___RECOVER__FILES__.jcrypt.txt
    • Includes a list of all files that are encryted

It avoids encrypting files with the following file extensions:

  • .jcrypt
  • %Desktop%\___RECOVER__FILES__.jcrypt.txt

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

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

18.392.04

FIRST VSAPI PATTERN DATE:

18 Apr 2023

VSAPI OPR PATTERN File:

18.393.00

VSAPI OPR PATTERN Date:

19 Apr 2023

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.XXPE50FFF067

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

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. DATA_GENERIC
  • Once located, select the file then press SHIFT+DELETE to delete it.
  • Repeat the said steps for all files listed.
    *Note: Read the following Microsoft page if these steps do not work on Windows 7 and Server 2008 (R2).

    • Step 5

    Scan your computer with your Trend Micro product to delete files detected as Ransom.MSIL.CYPREN.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 6

    Restore encrypted files from backup.


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