RANSOM_ONCRYPT.A

 Analysis by: Marvelous Pelin

 ALIASES:

Ransom.CryptonLock(Malwarebytes)

 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

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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 connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

299,874 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Feb 2017

Payload:

Encrypts files, Renames encrypted files, Displays message/message boxes

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:

  • {folders containing encrypted files}\COMO_ABRIR_ARQUIVOS.txt - ransom note
  • {location of malware}\SZVWW4PWKURN8JC7B.bmp - used as wallpaper
  • {location of malware}\{name of malware}.exe.bat
  • {location of malware}\cached-consensus
  • {location of malware}\COMO_ABRIR_ARQUIVOS.txt - ransom note

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = {location of malware}\SZVWW4PWKURN8JC7B.bmp

Other Details

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

  • http://{BLOCKED}ng5hswe3jv.onion/index.php
  • {BLOCKED}.{BLOCKED}.244.244
  • {BLOCKED}.{BLOCKED}.193.9

It renames encrypted files using the following names:

  • {original filename and extension}.id-{unique identifier}_steaveiwalker@india.com_

It does the following:

  • Avoids encrypting files with the following strings in their filepath:
    • all users
    • intel
    • nvidia
    • \program
    • \windows
  • Avoids encrypting files with the following filename:
    • boot.ini
    • Bootfont.bin
    • bootmgr
    • BOOTNXT
    • BOOTSECT.BAK
    • NTEDETECT.COM
    • ntldr
    • NTUSER.DAT
    • PDOXUSRS.NET
  • Avoids encrypting files with the following extensions:
    • .com
    • .sys

NOTES:

It sets the victim's desktop background to the following:

It displays the following as ransom note:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

13.226.00

FIRST VSAPI PATTERN DATE:

16 Feb 2017

VSAPI OPR PATTERN File:

13.227.00

VSAPI OPR PATTERN Date:

17 Feb 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

Restart in Safe Mode

[ Learn More ]

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.
  • {folders containing encrypted files}\COMO_ABRIR_ARQUIVOS.txt
  • {location of malware}\cached-consensus
  • {location of malware}\COMO_ABRIR_ARQUIVOS.txt
  • {location of malware}\SZVWW4PWKURN8JC7B.bmp
  • {location of malware}\{name of malware}.exe.bat

Step 5

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

Reset your Desktop properties

[ Learn More ]

Step 7

Restore encrypted files from backup.


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