Ransom.Win32.MEGACRYPTOR.THABAOAH

June 12, 2019
 Analysis by: Jemimah Mae Molina
 ALIASES:

W32/FilecoderPib.E40C!tr.ransom (FORTINET); Trojan-Ransom.FileCoder (IKARUS)

 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, 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 encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

424,448 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

10 Dec 2018

Payload:

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:

  • cmd.exe /c %User Profile%\DECRYPT.html
  • cmd.exe /C timeout /T 15 /NOBREAK && del {malware path}\{malware name} /F

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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

  • bip

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
inf = %User Profile%\Information.html

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
inf = %User Profile%\Information.html

Other Details

This Ransomware does the following:

  • It encrypts files in all drives.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .gdb
  • .ldf
  • .mdf
  • .mdb
  • .pdf
  • .fdb
  • .mde
  • .txt
  • .png
  • .jpg
  • .jpeg
  • .bmp
  • .gif
  • .zip
  • .rar
  • .1cd
  • .sql
  • .bak
  • .back
  • .cab
  • .log
  • .ico
  • .old
  • .rtf
  • .lnk
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .tif
  • .vsc
  • .mkv
  • .flac
  • .der
  • .sch
  • .crt
  • .pem
  • .pbix
  • .hbk
  • .epx
  • .dpl
  • .bpl
  • .htm
  • .csv
  • .mp4
  • .mp3
  • .myi
  • .myd
  • .xml
  • .r11
  • .vsl
  • .newdb
  • .srf
  • .pst
  • .ods
  • .erf
  • .html
  • .php
  • .asp
  • .aspx
  • .ppt
  • .pptx
  • .java
  • .cpp
  • .css
  • .jar
  • .swift
  • .shtml
  • .less
  • .sass
  • .dat
  • .json
  • .key
  • .avi
  • .3gp
  • .wmv
  • .accdb
  • .rmvb
  • .mpg
  • .mov
  • .vob
  • .flv
  • .swf
  • .wma
  • .aac
  • .mmf
  • .amr
  • .m4a
  • .m4r
  • .ogg
  • .mp2
  • .wav
  • .pcx
  • .tga
  • .tiff
  • .odt
  • .dll
  • .exe
  • .lrf
  • .glf
  • .msi
  • .vhdx
  • .vhd
  • .bin
  • .vsv
  • .tib
  • .vue

It renames encrypted files using the following names:

  • {encrypted file}.bip

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

  • {encrypted directory}\Information.html

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.680.03

FIRST VSAPI PATTERN DATE:

10 Dec 2018

VSAPI OPR PATTERN File:

14.681.00

VSAPI OPR PATTERN Date:

11 Dec 2018

Step 1

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 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

Delete this registry value

[ 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • inf = %User Profile%\Information.html
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • inf = %User Profile%\Information.html

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.
  • {encrypted directory}\Information.html

Step 5

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.MEGACRYPTOR.THABAOAH. 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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