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Ransom.Win32.NEFILIM.A

April 10, 2020
 Analysis by: Alyssa Christelle Ramos
 ALIASES:

Trojan-Ransom.Nemty(IKARUS); Ransom:MSIL/NefiCrypt.PI!MSR(MICROSOFT)

 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:

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 deletes itself after execution.

It drops files as ransom note. It avoids encrypting files with the following file extensions.

  TECHNICAL DETAILS

File Size:

72,672 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

13 Mar 2020

Payload:

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 adds the following processes:

  • "%System%\cmd.exe" /c timeout /t 3 /nobreak && del "{Full Path of Malware}\{Malware name}.exe" /s /f /q

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Den'gi plyvut v karmany rekoy. My khodim po krayu nozha...

Other Details

This Ransomware does the following:

  • It encrypts the following Drives:
    • Fixed Drive
    • Removable Drive
    • Remote/Network Drive

It deletes itself after execution.

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file path:

  • Windows
  • $RECYCLE BIN
  • rsa
  • ntdetect.com
  • ntdlr
  • MSDOS.SYS
  • IO.SYS
  • boot.ini
  • AUTOEXEC.BAT
  • ntuser.dat
  • desktop.ini
  • CONFIG.SYS
  • RECYCLER
  • BOOTSECT.BAK
  • bootmgr
  • Programdata
  • Appdata
  • Program files
  • Program files (x86)
  • Microsoft
  • sophos

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

  • {Drive Letter}\NEFILIM-DECRYPT.txt

It avoids encrypting files with the following file extensions:

  • .exe
  • .dll
  • .msi
  • .lnk
  • .mp3
  • .mp4
  • .pif
  • .ttf
  • .ini
  • .cpl
  • .com
  • .cab
  • .log
  • .cmd
  • .url
  • .NEFILIM

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.740.08

FIRST VSAPI PATTERN DATE:

13 Mar 2020

VSAPI OPR PATTERN File:

15.741.00

VSAPI OPR PATTERN Date:

14 Mar 2020

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.Win32.TRX.XXPE50FFF034

Step 2

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 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

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.
  • {Drive Letter}\NEFILIM-DECRYPT.txt

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.NEFILIM.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 the following Trend Micro Support pages for more information:

Step 6

Restore encrypted files from backup.


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