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RANSOM_FLATTENWARE.A

September 05, 2017
 Analysis by: Wilbert Vidal
 ALIASES:

MSIL.Trojan-Ransom.Cryptear.H (GData)

 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 connects to certain websites to send and receive information. It is capable of encrypting files in the affected system.

It encrypts files with specific file extensions. It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

937,984 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Aug 2017

Payload:

Encrypts files, Displays windows

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.

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Update = {Malware Path}

Other Details

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

  • http://www.{BLOCKED}u.xn--6frz82g/listen/listen.php

It is capable of encrypting files in the affected system.

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .pst
  • .ost
  • .msg
  • .eml
  • .vsd
  • .vsdx
  • .txt
  • .csv
  • .rtf
  • .123
  • .wks
  • .wk1
  • .pdf
  • .dwg
  • .onetoc2
  • .snt
  • .jpeg
  • .jpg
  • .docb
  • .docm
  • .dot
  • .dotm
  • .dotx
  • .xlsm
  • .xlsb
  • .xlw
  • .xlt
  • .xlm
  • .xlc
  • .xltx
  • .xltm
  • .pptm
  • .pot
  • .pps
  • .ppsm
  • .ppsx
  • .ppam
  • .potx
  • .potm
  • .edb
  • .hwp
  • .602
  • .sxi
  • .sti
  • .sldx
  • .sldm
  • .sldm
  • .vdi
  • .vmdk
  • .vmx
  • .gpg
  • .aes
  • .ARC
  • .PAQ
  • .bz2
  • .tbk
  • .bak
  • .tar
  • .tgz
  • .gz
  • .7z
  • .rar
  • .zip
  • .backup
  • .iso
  • .vcd
  • .bmp
  • .png
  • .gif
  • .raw
  • .cgm
  • .tif
  • .tiff
  • .nef
  • .psd
  • .ai
  • .svg
  • .djvu
  • .m4u
  • .m3u
  • .mid
  • .wma
  • .flv
  • .3g2
  • .mkv
  • .3gp
  • .mp4
  • .mov
  • .avi
  • .asf
  • .mpeg
  • .vob
  • .mpg
  • .wmv
  • .fla
  • .swf
  • .wav
  • .mp3
  • .sh
  • .class
  • .jar
  • .java
  • .rb
  • .asp
  • .php
  • .jsp
  • .brd
  • .sch
  • .dch
  • .dip
  • .pl
  • .vb
  • .vbs
  • .ps1
  • .bat
  • .cmd
  • .js
  • .asm
  • .h
  • .pas
  • .cpp
  • .c
  • .cs
  • .suo
  • .sln
  • .ldf
  • .mdf
  • .ibd
  • .myi
  • .myd
  • .frm
  • .odb
  • .dbf
  • .db
  • .mdb
  • .accdb
  • .sql
  • .sqlitedb
  • .sqlite3
  • .asc
  • .lay6
  • .lay
  • .mml
  • .sxm
  • .otg
  • .odg
  • .uop
  • .std
  • .sxd
  • .otp
  • .odp
  • .wb2
  • .slk
  • .dif
  • .stc
  • .sxc
  • .ots
  • .ods
  • .3dm
  • .max
  • .3ds
  • .uot
  • .stw
  • .sxw
  • .ott
  • .odt
  • .pem
  • .p12
  • .csr
  • .crt
  • .key
  • .pfx
  • .der
  • .dll
  • .mui

It encrypts files found in the following folders:

  • %User Profile%\Recent
  • %User Profile%\My Pictures
  • %User Profile%\My Music
  • %User Profile%\My Videos
  • %User Profile%\My Videos
  • %User Profile%\Personal
  • %User Profile%\Favorites
  • %User Profile%\Dropbox
  • C:\Users\Public\Public Desktop
  • C:\Users\Public\Public Pictures
  • C:\Users\Public\Public Documents
  • C:\Users\Public\Public Music
  • C:\Users\Public\Public Videos
  • C:\%Program Files%\Windows Defender"

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

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

  • .flat

NOTES:

This ransomware displays the following window applications as ransom note:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.612.04

FIRST VSAPI PATTERN DATE:

23 Aug 2017

VSAPI OPR PATTERN File:

13.613.00

VSAPI OPR PATTERN Date:

24 Aug 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 Safe Mode

[ Learn More ]

Step 4

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
    • Microsoft Update = {Malware Path}

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_FLATTENWARE.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.


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