Analysis by: Nikko Tamana
 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.

  TECHNICAL DETAILS

File Size: 1111552 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Jul 2017
Payload: Restarts system, Executes files, Displays message/message boxes, Encrypts files

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 file(s)/component(s):

  • %System Root%\xampp\dcapi.dll
  • %System Root%\xampp\dccon.exe - DiskCryptor Console
  • %System Root%\xampp\dcinst.exe
  • %System Root%\xampp\dcrypt.sys
  • %System Root%\xampp\log.txt
  • %System%\drivers\dcrypt.sys

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

Autostart Technique

This Ransomware registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
ImagePath = %System%\drivers\dcrypt.sys

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
ImagePath = {Malware Path and Filename}.exe {password} /accepteula

It adds and runs the following services:

  • DefragmentService
  • DiskCryptor driver

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\config

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Instances

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Security

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Enum

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService\Security

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService\Enum

It adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
Type = 00000001

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
Start = 00000000

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
ErrorControl = 00000003

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
DisplayName = DiskCryptor driver

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
Group = Filter

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
DependOnService = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt
DependOnGroup = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\config
Flags = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\config
Hotkeys = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\config
sysBuild = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Instances
DefaultInstance = dcrypt

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Instances\
dcrypt
Altitude = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Instances\
dcrypt
Flags = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Security
Security = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Enum
0 = {string values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Enum
Count = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\dcrypt\Enum
NextInstance = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
Type = 00000010

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
Start = 00000002

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
ErrorControl = 00000000

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
DisplayName = DefragmentService

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
ObjectName = LocalSystem

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService
FailureActions = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService\Security
Security = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService\Enum
0 = {string values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService\Enum
Count = 00000001

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DefragmentService\Enum
NextInstance = 00000001

Other Details

This Ransomware does the following:

  • Reboots the system to successfully install the Disk Cryptor
  • After reboot, it will execute the following:
  • - %System Root%\xampp\dccon.exe -boot -setmbr hd0
  • - %System Root%\xampp\dccon.exe -encrypt pt{0-9}-p {parameter}
  • It uses the tool %System Root%\xampp\dccon.exe to encrypt the disk drive and modify the Master Boot Record to display the ransom note.

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

NOTES:

After another reboot, this ransomware displays the following ransom note upon boot up:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.568.08
FIRST VSAPI PATTERN DATE: 29 Jul 2017
VSAPI OPR PATTERN File: 13.569.00
VSAPI OPR PATTERN Date: 30 Jul 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

Restore your system's Master Boot Record (MBR)

To restore your system's Master Boot Record (MBR):

• On Windows 2000, XP, and Server 2003:

  1. Insert your Windows Installation CD into your CD drive then restart your computer.
  2. When prompted, press any key to boot from the CD.
  3. On the Main Menu, type r to enter the Recovery Console.
    (Note for Windows 2000: After pressing r, type c to choose the Recovery Console on the repair options screen.)
  4. Type the number that corresponds to the drive and folder that contains Windows (usually C:\WINDOWS) and press Enter.
  5. Type your Administrator password and press Enter.
  6. In the input box, type the following then press Enter:
    fixmbr {affected drive}
  7. Type exit and press Enter to restart the system normally.

• On Windows Vista, 7, and Server 2008:

  1. Insert your Windows Installation DVD into the DVD drive, then press the restart button on your computer.
  2. When prompted, press any key to boot from the DVD.
  3. Depending on your Windows Installation DVD, you might be required to choose the installation language. On the Install Windows window, choose your language, locale, and keyboard layout or input method. Click Repair your computer.
  4. Select Use recovery tools that can help fix problems starting Windows. Select your installation of Windows. Click Next.
  5. If the Startup Repair window appears, click Cancel, Yes, then Finish.
  6. In the System Recovery Options menu, click Command Prompt.
  7. In the Command Prompt window, type the following then press Enter:
    BootRec.exe /fixmbr
  8. Type exit and press Enter to close the Command Prompt window.
  9. Click Restart to restart your computer normally.

• On Windows 8, 8.1, and Server 2012:

  1. Insert your Windows Installation DVD in the DVD drive, then restart your computer.
  2. When prompted, press any key to boot from the DVD.
  3. Depending on your Windows Installation DVD, you might be required to select the keyboard layout. Then on the Windows Setup window, choose your language, locale, and input method. Click Next, then click Repair your computer.
  4. Click Troubleshoot>Advanced Options>Command Prompt.
  5. In the Command Prompt window, type the following then press Enter:
    BootRec.exe /fixmbr
  6. Type exit and press Enter to close the Command Prompt window.
  7. Click Continue to restart the system normally.

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

Restart in Safe Mode

[ Learn More ]

Step 5

Disable this malware service

[ Learn More ]
  •  
    • DiskCryptor driver
    • DefragmentService

Step 6

Delete this registry key

[ 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\SYSTEM\ControlSet001\Services
    • dcrypt
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services
    • DefragmentService

Step 7

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.
  • %System Root%\xampp\dcapi.dll
  • %System Root%\xampp\dccon.exe
  • %System Root%\xampp\dcinst.exe
  • %System Root%\xampp\dcrypt.sys
  • %System Root%\xampp\log.txt
  • %System%\drivers\dcrypt.sys

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_HDDCRYPTOR.AUSE. 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.


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