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Ransom.Win32.MEGACORTEX.AD

November 09, 2019
 ALIASES:

Trojan.Win32.DelShad.bnv (Kaspersky); Mal/Cleaman-B (Sophos)

 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.

  TECHNICAL DETAILS

File Size:

1,944,576 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Nov 2019

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 adds the following processes:

  • net user {username} ATa9WdAr/ez/0BvG
  • %System%\net1 user {username} ATa9WdAr/ez/0BvG
  • %System%\vssadmin.exe delete shadows /all /quiet
  • reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /f /t REG_SZ /v legalnoticecaption /d "Locked By MegaCortex"
  • reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /f /t REG_SZ /v legalnoticetext /d "Contact: Borismcfallen@mail.com or Kirkmansion@mail.com"
  • "%User Temp%\60418d5079f3fe8a824d74bd3dd4d495021a285a.exe" +
  • net stop "SamSs" /y
  • %System%\net1 stop "SamSs" /y
  • %System%\net1 stop "SDRSVC" /y
  • %System%\net1 stop "SstpSvc" /y
  • %System%\net1 stop "UI0Detect" /y
  • %System%\net1 stop "wbengine" /y
  • %System%\net1 stop "NetMsmqActivator" /y
  • %System%\net1 stop "WinDefend" /y
  • %System%\net1 stop "BITS" /y

Other System Modifications

This Ransomware modifies the following file(s):

  • %Windows%\Temp\r_s0bkq5M6-1.cmd

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

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
legalnoticecaption = "Locked By MegaCortex"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
legalnoticetext = "Contact: Borismcfallen@mail.com or Kirkmansion@mail.com"

Dropping Routine

This Ransomware drops the following files:

  • %Windows%\Temp\r_s0bkq5M6-1.cmd

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

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.850

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

Identify and terminate files detected as Ransom.Win32.MEGACORTEX.AD

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • legalnoticecaption = "Locked By MegaCortex"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
    • legalnoticetext = "Contact: Borismcfallen@mail.com or Kirkmansion@mail.com"

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.
  • %Windows%\Temp\r_s0bkq5M6-1.cmd

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.MEGACORTEX.AD. 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.

Step 7

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %Windows%\Temp\r_s0bkq5M6-1.cmd


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