RANSOM_CRYPTRITU.A

This is the Trend Micro detection for the latest variant of ransomware that is written in JavaScript. Based on reports, it has capabilities to run on Windows, Mac OS X and Linux.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

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 modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information.

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:

• %Application Data%\Chrome Browser\chrome - copy of the GPL licensing agreement
• %Application Data%\Chrome Browser\chrome.exe - NW.js package application contains the actual malicious routine.
• %Application Data%\Chrome Browser\icudtd.dat - NW.js framework component
• %Application Data%\Chrome Browser\ffmpegsumo.dll - NW.js framework component
• %Application Data%\Chrome Browser\nw.pak - NW.js framework component
• %Application Data%\Chrome Browser\g - config file (Bitcoin address, Error Message, Affiliate ransom amount)
• %Application Data%\Chrome Browser\rundll32.exe - Renamed TOR client used for C2 communication
• %Application Data%\Chrome Browser\msgbox.vbs - script used to display the Error Message
• %Application Data%\Chrome Browser\s.exe - used to drop the shortcut file in %User Startup% folder
• %Application Data%\Chrome Browser\u.vbs - Enumerates and deletes all files and folder in the specified directory.

(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.. %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It creates the following folders:

• %Application Data%\Chrome Browser

(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.)

Autostart Technique

This Trojan drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

• ChromeService.lnk - shortcut file that points to %Application Data%\Chrome Browser\chrome.exe

(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.)

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

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

• http://{BLOCKED}.{BLOCKED}.40.189:443
• http://{BLOCKED}.{BLOCKED}.244.244:443
• http://{BLOCKED}.{BLOCKED}.105.57:9001
• http://{BLOCKED}.{BLOCKED}.92.11:9101
• http://{BLOCKED}.{BLOCKED}.93.36:9001
• http://{BLOCKED}.{BLOCKED}.92.11:9001
• http://{BLOCKED}.{BLOCKED}.18.110:80

It encrypts files with the following extensions:

• *.jpg
• *.jpeg
• *.raw
• *.tif
• *.gif
• *.png
• *.bmp
• *.3dm
• *.max
• *.accdb
• *.db
• *.dbf
• *.mdb
• *.pdb
• *.sql
• *.*sav*
• *.*spv*
• *.*grle*
• *.*mlx*
• *.*sv5*
• *.*game*
• *.*slot*
• *.dwg
• *.dxf
• *.c
• *.cpp
• *.cs
• *.h
• *.php
• *.asp
• *.rb
• *.java
• *.jar
• *.class
• *.aaf
• *.aep
• *.aepx
• *.plb
• *.prel
• *.prproj
• *.aet
• *.ppj
• *.psd
• *.indd
• *.indl
• *.indt
• *.indb
• *.inx
• *.idml
• *.pmd
• *.xqx
• *.xqx
• *.ai
• *.eps
• *.ps
• *.svg
• *.swf
• *.fla
• *.as3
• *.as
• *.txt
• *.doc
• *.dot
• *.docx
• *.docm
• *.dotx
• *.dotm
• *.docb
• *.rtf
• *.wpd
• *.wps
• *.msg
• *.pdf
• *.xls
• *.xlt
• *.xlm
• *.xlsx
• *.xlsm
• *.xltx
• *.xltm
• *.xlsb
• *.xla
• *.xlam
• *.xll
• *.xlw
• *.ppt
• *.pot
• *.pps
• *.pptx
• *.pptm
• *.potx
• *.potm
• *.ppam
• *.ppsx
• *.ppsm
• *.sldx
• *.sldm
• *.wav
• *.mp3
• *.aif
• *.iff
• *.m3u
• *.m4u
• *.mid
• *.mpa
• *.wma
• *.ra
• *.avi
• *.mov
• *.mp4
• *.3gp
• *.mpeg
• *.3g2
• *.asf
• *.asx
• *.flv
• *.mpg
• *.wmv
• *.vob
• *.m3u8
• *.csv
• *.efx
• *.sdf
• *.vcf
• *.xml
• *.ses
• *.dat

NOTES:

It avoids encrypting files in the directories that contain the following strings:
:\windows\
:\winnt\
programdata\
boot\
temp\
tmp\
$recycle.bin\

It executes the following command:

• to cscript msgbox.vbs 16 {ERROR MESSAGE}

Where {ERROR MESSAGE}depends on the config file.

After its encryption routine it displays the following Window containing ransom notes and information on how to recover the encrypted files.