Analysis by: Martin Xavier Co

ALIASES:

Ransom:Win32/Genasom (Microsoft); Win32.Trojan-Ransom.LockCrypt.A (GData)

 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: 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.

It modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 48,128 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Aug 2017
Payload: Drops files, Encrypts files, Connects to URLs/IPs

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:

  • {malware current directory}\W.bat
  • {folder of encrypted files}\ReadMe.TxT
  • %System Root%\ReadMe.TxT
  • %Windows%\bfsvcm.exe

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

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
unlock = "%Windows%\notepad.exe" c:\ReadMe.TxT

Other System Modifications

This Ransomware modifies the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Hacked = {random characters}

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
LegalNoticeCaption = "Attention!!! Your files are encrypted !!!"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
LegalNoticeText = To recover files, follow the prompts in the text file "Readme"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,c:\Windows\bfsvcm.exe,"

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • sqlbrowser.exe

Web Browser Home Page and Search Page Modification

This Ransomware modifies the Internet Explorer Zone Settings.

Other Details

This Ransomware connects to the following website to send and receive information:

  • {BLOCKED}.{BLOCKED}.17.222:21010

It executes the following command to disable/stop/delete Windows components:

  • vssadmin delete shadows /all

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • windows
  • ReadMe.TxT
  • lock

It renames encrypted files using the following names:

  • {random characters} ID {random characters}.lock

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

NOTES:
This ransomware displays the following before logging in:

This ransomware will then display the following window while encrypting files:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.598.01
FIRST VSAPI PATTERN DATE: 15 Aug 2017
VSAPI OPR PATTERN File: 13.599.00
VSAPI OPR PATTERN Date: 16 Aug 2017

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 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

Scan your computer with your Trend Micro product to delete files detected as RANSOM_LOCKCRYPT.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 this Knowledge Base page for more information.

Step 4

Search and delete this file

[ 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.  
  • {malware current directory}\W.bat
  • {folder of encrypted files}\ReadMe.TxT
  • %System Root%\ReadMe.TxT

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_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Hacked = {random characters}
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • LegalNoticeCaption = "Attention!!! Your files are encrypted !!!"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • LegalNoticeText = To recover files, follow the prompts in the text file "Readme"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • unlock = "%Windows%\notepad.exe" c:\ReadMe.TxT

Step 6

Restore this modified 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_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,c:\Windows\bfsvcm.exe,"
      To: Userinit = "%System%\userinit.exe,"

Step 7

Restore encrypted files from backup.


Did this description help? Tell us how we did.