Analysis by: Marcus Ma. Antonio Capistrano
ALIASES:

Trojan.RansomKD.12725364 (BITDEFENDER), a variant of Win32/Filecoder.NOW trojan (NOD32), W32/Filecoder.NOW!tr (FORTINET)

 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.

It is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size: 2,817,024 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 04 Jan 2018
Payload: Displays windows, 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 stays resident in memory by creating the following process(es):

  • {malware file path} --Admin
  • {malware file path} --Service {Process ID of malware}

Other Details

This Ransomware does the following:

  • The Ransomware requires user interaction to start its encryption routine; it requires all of fields to be filled.
  • By default, the Ransomware avoids encrypting files in the following directories:
    C:\Windows\
    C:\Program Files (x86)\Mozilla Firefox\
    C:\Program Files (x86)\Internet Explorer\
    C:\Program Files (x86)\Google\
    C:\Program Files\Mozilla Firefox\
    C:\Program Files\Internet Explorer\
    C:\Program Files\Google\
    D:\Windows\
    D:\Program Files (x86)\Mozilla Firefox\
    D:\Program Files (x86)\Internet Explorer\
    D:\Program Files (x86)\Google\
    D:\Program Files\Mozilla Firefox\
    D:\Program Files\Internet Explorer\
    D:\Program Files\Google\
  • Upon execution of the ransomware, it displays the following window:

It 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:

  • {user specified extension}

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

  • {all directories excluding avoided directories}\{user specified File Name}

It leaves text files that serve as ransom notes containing the following text:

  • {user specified ransom note}

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.886.04
FIRST VSAPI PATTERN DATE: 05 Jan 2018
VSAPI OPR PATTERN File: 13.887.00
VSAPI OPR PATTERN Date: 06 Jan 2018

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

Identify and terminate files detected as RANSOM_FILECODER.THAOEH

[ 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 4

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.  
  • {all directories excluding avoided directories}\{user specified File Name}

Step 5

Scan your computer with your Trend Micro product to delete files detected as RANSOM_FILECODER.THAOEH. 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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