Analysis by: Clive Fuentebella
ALIASES:

Win32:Trojan-gen (AVAST); Trojan.Python.Agent (IKARUS)

 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

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: 5,050,198 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Mar 2020

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:

  • %User Temp%\_MEI{Random number}\1.exe.manifest
  • %User Temp%\_MEI{Random number}\Microsoft.VC90.CRT.manifest
  • %User Temp%\_MEI{Random number}\_ctypes.pyd
  • %User Temp%\_MEI{Random number}\_hashlib.pyd
  • %User Temp%\_MEI{Random number}\_socket.pyd
  • %User Temp%\_MEI{Random number}\_ssl.pyd
  • %User Temp%\_MEI{Random number}\bz2.pyd
  • %User Temp%\_MEI{Random number}\msvcm90.dll
  • %User Temp%\_MEI{Random number}\msvcp90.dll
  • %User Temp%\_MEI{Random number}\msvcr90.dll
  • %User Temp%\_MEI{Random number}\python27.dll
  • %User Temp%\_MEI{Random number}\select.pyd
  • %User Temp%\_MEI{Random number}\unicodedata.pyd
  • %User Temp%\_MEI{Random number}\Include\pyconfig.h
  • %User Temp%\_MEI{Random number}\certifi\cacert.pem
  • %User Temp%\{Random character}
  • %User Temp%\tmp{Random number}.dll
  • %System%\Chop.BAIP
  • %Desktop%\HowToDecrypt.txt
  • {Drive letter}:\HowToDecrypt.txt

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

It adds the following processes:

  • "{Malware file path and name}"
  • sc stop "Microsoft Exchange Active Directory Toplogy"
  • sc stop "Microsoft Exchange Anti-spam Update"
  • sc stop "Microsoft Exchange Compliance Audit"
  • sc stop "Microsoft Exchange Compliance Service"
  • sc stop "Microsoft Exchange DAG Management"
  • sc stop "Microsoft Exchange Diagnostics"
  • sc stop "Microsoft Exchange EdgeSync"
  • sc stop "Microsoft Exchange Frontend Transport"
  • sc stop "Microsoft Exchange Health Manager"
  • sc stop "Microsoft Exchange Health Manager Recovery"
  • sc stop "Microsoft Exchange IMAP4"
  • sc stop "Microsoft Exchange IMAP4 Backend"
  • sc stop "Microsoft Exchange Information Store"
  • sc stop "Microsoft Exchange Mailbox Assistants"
  • sc stop "Microsoft Exchange Mailbox Replication"
  • sc stop "Microsoft Exchange Mailbox Transport Delivery"
  • sc stop "Microsoft Exchange POP3"
  • sc stop "Microsoft Exchange POP3 Backend"
  • sc stop "SQL Server Agent (TESTINSTANCE)"
  • sc stop "SQL Server (TESTINSTANCE)"

Other Details

This Ransomware connects to the following possibly malicious URL:

  • http://mnmski.{BLOCKED}4.com:443

Ransomware Routine

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

  • .vhd

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.762.04
FIRST VSAPI PATTERN DATE: 24 Mar 2020
VSAPI OPR PATTERN File: 15.763.00
VSAPI OPR PATTERN Date: 25 Mar 2020

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

Restart in Safe Mode

[ Learn More ]

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.  
  • %User Temp%\_MEI{Random number}\1.exe.manifest
  • %User Temp%\_MEI{Random number}\Microsoft.VC90.CRT.manifest
  • %User Temp%\_MEI{Random number}\_ctypes.pyd
  • %User Temp%\_MEI{Random number}\_hashlib.pyd
  • %User Temp%\_MEI{Random number}\_socket.pyd
  • %User Temp%\_MEI{Random number}\_ssl.pyd
  • %User Temp%\_MEI{Random number}\bz2.pyd
  • %User Temp%\_MEI{Random number}\msvcm90.dll
  • %User Temp%\_MEI{Random number}\msvcp90.dll
  • %User Temp%\_MEI{Random number}\msvcr90.dll
  • %User Temp%\_MEI{Random number}\python27.dll
  • %User Temp%\_MEI{Random number}\select.pyd
  • %User Temp%\_MEI{Random number}\unicodedata.pyd
  • %User Temp%\_MEI{Random number}\Include\pyconfig.h
  • %User Temp%\_MEI{Random number}\certifi\cacert.pem
  • %User Temp%\{Random character}
  • %User Temp%\tmp{Random number}.dll
  • %System%\Chop.BAIP
  • %Desktop%\HowToDecrypt.txt
  • {Drive letter}:\HowToDecrypt.txt

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.VHDLOCKER.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 6

Restore encrypted files from backup.


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