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Ransom.Win32.CRYLOCK.H

April 23, 2022
 Analysis by: Jeffrey Francis Bonaobra
 ALIASES:

Ransom:Win32/Crylock.PAA!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

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 is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

201,728 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

22 Apr 2022

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:

  • %Windows%\Logs\WindowsBackup\Wbadmin.0.etl
  • %User Temp%\{Drive Letter}-{Random Numbers}.log

(Note: %Windows% is the Windows folder, where it usually is C:\Windows 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).)

It adds the following processes:

  • %System%\cmd.exe /c "vssadmin delete shadows /all /quiet"
  • %System%\cmd.exe /c "wbadmin DELETE SYSTEMSTATEBACKUP -keepVersions:0"
  • %System%\cmd.exe /c "wbadmin DELETE BACKUP keepVersions:0"
  • %System%\cmd.exe /c "wmic SHADOWCOPY DELETE"
  • %System%\cmd.exe /c "bcdedit /set {default} recoveryenabled No"
  • %System%\cmd.exe /c "bcdedit /set {default} bootstatuspolicy ignoreallfailures"

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other Details

This Ransomware is capable of encrypting files in the affected system.

Ransomware Routine

This Ransomware renames encrypted files using the following names:

  • {Original Filename}.{Original File Extension}[hopeandhonest@smime.ninja].[{Generated ID}]

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

  • %User Temp%\how_to_decrypt.hta
  • {Drive Letter}\how_to_decrypt.hta

(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).)

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.520.04

FIRST VSAPI PATTERN DATE:

22 Apr 2022

VSAPI OPR PATTERN File:

17.521.00

VSAPI OPR PATTERN Date:

23 Apr 2022

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.XXPE50FFF055

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.
  • %Windows%\Logs\WindowsBackup\Wbadmin.0.etl
  • %User Temp%\{Drive Letter}-{Random Numbers}.log
  • %User Temp%\how_to_decrypt.hta
  • {Drive Letter}\how_to_decrypt.hta

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.CRYLOCK.H. 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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