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RANSOM_CRYPNTK.A

February 28, 2017
 Analysis by: Julie Anne Cabuhat
 ALIASES:

Ransom.FileCryptor (Malwarebytes), Ransom:Win32/FileCryptor (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This Trojan 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.

  TECHNICAL DETAILS

File Size:

31,232 bytes

Memory Resident:

Yes

Initial Samples Received Date:

17 Feb 2017

Payload:

Encrypts files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Other Details

This Trojan renames encrypted files using the following names:

  • {Original filename and extension}.powned

It is capable of encrypting files in the affected system.

NOTES:

In order to run properly, it checks the existence of the following: C:\Utilisateurs\Administrateur\Documents

The ransomware encrypts files in the following locations:

  • %User Profiles%\Documents
  • %User Profiles%\Music
  • %User Profiles%\Pictures
  • %User Profiles%\Downloads
  • %Desktop%
  • D:\

    • It avoids encrypting the following file:

  • desktop.ini

    • After encryption, it displays the following message box:

    It uses the following decryption key:

  • s5q21788e5z662s315d4876e56z8d7sd2542

    •   SOLUTION

    Minimum Scan Engine:

    9.850

    FIRST VSAPI PATTERN FILE:

    13.226.08

    FIRST VSAPI PATTERN DATE:

    17 Feb 2017

    VSAPI OPR PATTERN File:

    13.227.00

    VSAPI OPR PATTERN Date:

    18 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 normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPNTK.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

    Restore encrypted files from backup.


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