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RANSOM_MAURI.A

April 06, 2018
 Analysis by: Marcus Ma. Antonio Capistrano
 ALIASES:

Trojan-Ransom.Win32.Crypmodadv.xoo (KASPERSKY), a variant of Win32/Filecoder.NOA trojan (NOD32), W32/Filecoder.NOA!tr (FORTINET)

 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:

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.

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

  TECHNICAL DETAILS

File Size:

3,792,384 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

30 Nov 2017

Payload:

Encrypts files, Connects to URLs/IPs

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:

  • %Desktop%\FILES_ENCRYPTED.html

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other Details

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

  • https://{BLOCKED}.{BLOCKED}.0.1:8080/api/keys/add

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • doc
  • docx
  • msg
  • odt
  • wpd
  • wps
  • txt
  • csv
  • pps
  • ppt
  • pptx
  • aif
  • iif
  • m3u
  • m4a
  • mid
  • mp3
  • mpa
  • wav
  • wma
  • 3gp
  • 3g2
  • avi
  • flv
  • m4v
  • mov
  • mp4
  • mpg
  • vob
  • wmv
  • 3dm
  • 3ds
  • max
  • obj
  • blend
  • bmp
  • gif
  • png
  • jpeg
  • jpg
  • psd
  • tif
  • gif
  • ico
  • ai
  • eps
  • ps
  • svg
  • pdf
  • indd
  • pct
  • epub
  • xls
  • xlr
  • xlsx
  • accdb
  • sqlite
  • dbf
  • mdb
  • pdb
  • sql
  • db
  • dem
  • gam
  • nes
  • rom
  • sav
  • bkp
  • bak
  • tmp
  • cfg
  • conf
  • ini
  • prf
  • html
  • php
  • js
  • c
  • cc
  • py
  • lua
  • go
  • java

It avoids encrypting files found in the following folders:

  • ProgramData
  • Windows
  • bootmgr
  • $WINDOWS.~BT
  • Windows.old
  • Temp
  • tmp
  • Program Files
  • Program Files (x86)
  • AppData
  • $Recycle.Bin

It appends the following extension to the file name of the encrypted files:

  • .encrypted

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

  • %Desktop%\READ_TO_DECRYPT.html

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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

  • YOUR FILES HAVE BEEN ENCRYPTED USING A
    STRONG AES-256 ALGORITHM.
    YOUR IDENTIFICATION IS
    {random string}
    SEND 0.345 BTC TO THE FOLLOWING WALLET
    FD0AhH61ona6fXS62RSQKhNF07Ijx5SBQO
    AND AFTER PAY CONTACT example@ywtpdnpwihbyuvck.onion
    SENDING YOUR IDENTIFICATION TO RECOVER
    THE KEY NECESSARY TO DECRYPT YOUR FILES

NOTES:

The ransomware is not able to proceed to its encryption routine.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.816.08

FIRST VSAPI PATTERN DATE:

01 Dec 2017

VSAPI OPR PATTERN File:

13.817.00

VSAPI OPR PATTERN Date:

02 Dec 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

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.  
  • %Desktop%\FILES_ENCRYPTED.html
  • %Desktop%\READ_TO_DECRYPT.html

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_MAURI.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 5

Restore encrypted files from backup.


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