Analysis by: Francis Xavier Antazo
ALIASES:

Ransom:Win32/Genasom (Microsoft); a variant of MSIL/Filecoder.DF (ESET); Ransomer.MHU (AVG); Ransom.FSociety (Malwarebytes);

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes then deletes itself afterward.

  TECHNICAL DETAILS

File Size: 28160 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 07 Nov 2016
Payload: Encrypts files, Displays graphics/image

Arrival Details

This Trojan 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 Trojan drops the following files:

  • {folders where it is able to encrypt files}\DECRYPT_YOUR_FILES.HTML

It drops and executes the following files:

  • {malware path}\delete.bat (deletes self)
  • %Application Data%\delback.dat (delete shadow backup)

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on 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 executes then deletes itself afterward.

Other Details

This Trojan encrypts files with the following extensions:

  • .txt
  • .qbw
  • .QBB
  • .qbb
  • .QBW
  • .TLG
  • .JPG
  • .tlg
  • .ecw
  • .pdf
  • .DBF
  • .PDF
  • .frm
  • .pix
  • .accdb
  • .mdb
  • .cdr
  • .eps
  • .tif
  • .msg
  • .asmx
  • .rpt
  • .arw
  • .qbo
  • .qbw
  • .sldprt
  • .dwf
  • .doc
  • .adi
  • .adt
  • .docx
  • .altr
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .odt
  • .jpg
  • .png
  • .csv
  • .sql
  • sln
  • .php
  • .asp
  • .aspx
  • .html
  • .xml
  • .psd
  • .bat
  • .js
  • .css
  • .sqlite
  • .dwg
  • .jpeg

It renames encrypted files using the following names:

  • {original filename and file extension}.dll

NOTES:

This ransomware deletes all shadow copies by executing the following command:

  • vssadmin delete shadows/all/quiet

It also displays the following image:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.902.07
FIRST VSAPI PATTERN DATE: 16 Nov 2016
VSAPI OPR PATTERN File: 12.903.00
VSAPI OPR PATTERN Date: 17 Nov 2016

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

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.  
  • {folders where it is able to encrypt files}\DECRYPT_YOUR_FILES.HTML
  • {malware path}\delete.bat
  • %Application Data%\delback.dat

Step 3

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

Step 4

Restore encrypted files from backup.


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