Analysis by: Julie Anne Cabuhat
ALIASES:

Luhe.Fiha.P (AVG), Ransom.FileCryptor (Malwarebytes), Ransom:Win32/FileCryptor (Microsoft)

 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

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.

  TECHNICAL DETAILS

File Size: 230,400 bytes
File Type: EXE
File Compression: UPX
Memory Resident: No
Initial Samples Received Date: 20 Jan 2017
Payload: Connects to URLs/IPs, Encrypts files, Displays message/message boxes

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.

Dropping Routine

This Trojan drops the following files:

  • {malware path}\trc.dll - list of files which extension is not for encryption and not for avoidance
  • {malware path}\rar.exe - WinRAR executable version 3.64
  • {malware path}\clsign.dll - Crypto key file
  • {hard drive letter}\clsign.dll
  • {malware path}\note.ini - Ransom note
  • {malware path}\wallet.jpg - QR code

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

  • http://whatismyip.net

It encrypts files with the following extensions:

  • .txt
  • .xls
  • .xlsx
  • .doc
  • .docx
  • .rtf
  • .ppt
  • .pptx
  • .pps
  • .gpg
  • .pgp
  • .c
  • .cpp
  • .asm
  • .cs
  • .php
  • .pas
  • .class
  • .py
  • .pl
  • .h
  • .vb
  • .vcproj
  • .vbproj
  • .java
  • .bak
  • .backup
  • .mdb
  • .accdb
  • .mdf
  • .odb
  • .wdb
  • .csv
  • .tsv
  • .sql
  • .psd
  • .eps
  • .cdr
  • .cpt
  • .indd
  • .dwg
  • .ai
  • .svg
  • .max
  • .skp
  • .scad
  • .cad
  • .3ds
  • .blend
  • .lwo
  • .lws
  • .mb
  • .db
  • .pptm
  • .pptx
  • .xlsb
  • .xlsm
  • .docm
  • .key
  • .asp
  • .tif
  • .vbs
  • .pdf
  • .epub
  • .mobi
  • .one
  • .zip
  • .rar
  • .htm
  • .aes

It renames encrypted files using the following names:

  • {Original filename and extension}.cry

It does the following:

  • It avoids files with the following extensions:
    • .cry
    • .exe
    • .dll
    • .sys
    • .com
    • .cpl
    • .theme
    • .ttf
    • .chm
    • .bat
    • .cmd
    • .gif
    • .ico
    • .lnk
    • .manifest
    • .msi
    • .scr
    • .tmp
    • .url
    • .inf
    • .ini
    • .torrent
    • .avi
    • .mp3
    • .flv
    • .mkv
    • .mov
    • .asf
    • .mpeg
    • .vob
    • .mpg
    • .gif
    • .raw
    • .srt
    • .sub
    • .3GP
    • .DIVX
    • .WMV
    • .rm
    • .m4v
    • .ocx
    • .tmp
    • .Manifest
    • .log
    • .ttf
    • .fon
    • .hlp
    • .chm
    • .chi
    • .reg
    • .url
    • .nfo
  • It uses WinRAR.exe to encrypt the files using the following command:
    • "{malware path}\rar.exe" a -m1 -df -dh -idcdpq -ep -hp{password} "{Original filename and extension}.cry" "{Original filename and extension}"
  • The parameters meaning the following:
    • a - add files to archive
    • m1 - compression level 1
    • df - delete files after archiving
    • dh - open shared files
    • idcdpq - disable messages
    • hp{password} - encrypt both file data and headers
  • It drops the following ransom note:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.192.00
FIRST VSAPI PATTERN DATE: 20 Jan 2017
VSAPI OPR PATTERN File: 13.193.00
VSAPI OPR PATTERN Date: 21 Jan 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.
  • {malware path}\trc.dll
  • {malware path}\rar.exe
  • {malware path}\clsign.dll
  • {hard drive letter}\clsign.dll
  • {malware path}\note.ini
  • {malware path}\wallet.jpg

Step 4

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

Restore encrypted files from backup.


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