Ransom_PURGE.W

 Analysis by: Nikko Tamana

 ALIASES:

Ransom:Win32/Contentocrypt.A (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:

  • 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:

539,437 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

19 Dec 2017

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 and executes the following files:

  • %System Root%\uneq\google.bat
  • %System Root%\uneq\Key.exe
  • %System Root%\uneq\update.vbs
  • %System Root%\uneq\run.vbs
  • %System Root%\uneq\lsassc.exe
  • %System Root%\uneq\lmxs.vbs
  • %System Root%\uneq\win.rar
  • %System Root%\uneq\java.bat
  • %AppDataLocal%\trust.exe

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Ransomware creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKCU\Software\Microsoft\
Windows\CurrentVersion\RunOnce
{EE750B8B-8F1F-4FEB-B415-B9B0FDBD4893} = %AppDataLocal%\trust.exe

Other Details

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

Ransomware Routine

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

  • .globe

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

  • {Encrypted file path}\How to restore files.hta

  SOLUTION

Minimum Scan Engine:

9.850

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

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\RunOnce
    • {EE750B8B-8F1F-4FEB-B415-B9B0FDBD4893} = %AppDataLocal%\trust.exe

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.
  • %System Root%\uneq\google.bat
  • %System Root%\uneq\Key.exe
  • %System Root%\uneq\update.vbs
  • %System Root%\uneq\run.vbs
  • %System Root%\uneq\lsassc.exe
  • %System Root%\uneq\lmxs.vbs
  • %System Root%\uneq\win.rar
  • %System Root%\uneq\java.bat
  • %AppDataLocal%\trust.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom_PURGE.W. 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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