Ransom.Win32.CRYPSHED.THGODAI

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.

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 copies of itself into the affected system:

• %All Users Profile%\Application Data\Windows\csrss.exe (Windows XP and below)
• %All Users Profile%\Windows\csrss.exe (Windows Vista and above)

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

It drops the following files:

• %User Temp%\{random}\lock
• %User Temp%\{random}\state
• %User Temp%\{random}\unverified-microdesc-consensus
• %User Temp%\{random}\cached-certs
• %User Temp%\{random}\cached-microdesc-consensus
• %User Temp%\{random}\cached-microdescs.new
• %Application Data%\{Random characters}.bmp

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

• %System%\cmd.exe chcp
• %System%\vssadmin.exe List Shadows
• %System%\vssadmin.exe Delete Shadows /All /Quiet

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Subsystem = "%All Users Profile%\Application Data\Windows\csrss.exe (Windows XP and below)"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Subsystem = "%All Users Profile%\Windows\csrss.exe (Windows Vista and above)"

Other System Modifications

This Ransomware adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xVersion = "4.0.0.1"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xpk = "{PUBLIC KEY}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xmode = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xi = "{Random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xstate = {number}

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xcnt = "{number}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
shsnt = "{number}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
shst = "{number}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
sh1 = "{number}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
sh2 = "{number}"

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Application Data%\{Random characters}.bmp

It sets the system's desktop wallpaper to the following image:

Other Details

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

• http://whatismyipaddress.com/
• http://whatsmyip.net/

It connects to the following website to send and receive information:

• http://{BLOCKED}p2xzclh6fd.onion/{path}
  where {path} can be any of the following:
  • reg.php
  • prog.php
  • err.php
  • cmd.php
  • sys.php
  • shd.php
  • mail.php

Ransomware Routine

This Ransomware encrypts files with the following extensions:

• .1cd
• .3ds
• .3fr
• .3g2
• .3gp
• .7z
• .accda
• .accdb
• .accdc
• .accde
• .accdt
• .accdw
• .adb
• .adp
• .ai
• .ai3
• .ai4
• .ai5
• .ai6
• .ai7
• .ai8
• .anim
• .arw
• .as
• .asa
• .asc
• .ascx
• .asm
• .asmx
• .asp
• .aspx
• .asr
• .asx
• .avi
• .avs
• .backup
• .bak
• .bay
• .bd
• .bin
• .bmp
• .bz2
• .c
• .cbf
• .cdr
• .cer
• .cf
• .cfc
• .cfm
• .cfml
• .cfu
• .chm
• .cin
• .class
• .clx
• .config
• .cpp
• .cr2
• .crt
• .crw
• .crypted
• .cs
• .css
• .csv
• .cub
• .dae
• .dat
• .db
• .dbf
• .dbx
• .dc3
• .dcm
• .dcr
• .der
• .dib
• .dic
• .dif
• .divx
• .djvu
• .dmp
• .dng
• .doc
• .docm
• .docx
• .dot
• .dotm
• .dotx
• .dpx
• .dqy
• .dsn
• .dt
• .dtd
• .dwg
• .dwt
• .dx
• .dxf
• .edml
• .efd
• .elf
• .emf
• .eml
• .emz
• .epf
• .eps
• .epsf
• .epsp
• .erf
• .exr
• .f4v
• .fbk
• .fdb
• .fido
• .fld
• .flm
• .flv
• .frm
• .fxg
• .geo
• .gif
• .grs
• .gz
• .h
• .hdr
• .hpp
• .hta
• .htc
• .htm
• .html
• .icb
• .ics
• .iff
• .inc
• .indd
• .ini
• .iqy
• .j2c
• .j2k
• .java
• .jp2
• .jpc
• .jpe
• .jpeg
• .jpf
• .jpg
• .jpx
• .js
• .jsf
• .json
• .jsp
• .kdc
• .kmz
• .kwm
• .lasso
• .lbi
• .lgf
• .lgp
• .log
• .lst
• .m1v
• .m4a
• .m4v
• .max
• .md
• .mda
• .mdb
• .mde
• .mdf
• .mdw
• .mef
• .mft
• .mfw
• .mht
• .mhtml
• .mka
• .mkidx
• .mkv
• .mos
• .mov
• .mp3
• .mp4
• .mpeg
• .mpg
• .mpv
• .mrw
• .msg
• .mtr
• .mxl
• .myd
• .myi
• .nef
• .nrw
• .obj
• .odb
• .odc
• .odm
• .odp
• .ods
• .oft
• .one
• .onepkg
• .onetoc2
• .opt
• .oqy
• .orf
• .p12
• .p7b
• .p7c
• .pam
• .pbm
• .pct
• .pcx
• .pdd
• .pdf
• .pdp
• .pef
• .pem
• .pff
• .pfm
• .pfx
• .pgm
• .php
• .php3
• .php4
• .php5
• .phtml
• .pict
• .pl
• .pls
• .pm
• .png
• .pnm
• .pot
• .potm
• .potx
• .ppa
• .ppam
• .ppm
• .pps
• .ppsm
• .ppt
• .pptm
• .pptx
• .prn
• .ps
• .psb
• .psd
• .pst
• .ptx
• .pub
• .pwm
• .pxr
• .py
• .qt
• .r3d
• .raf
• .rar
• .raw
• .rdf
• .rgbe
• .rle
• .rqy
• .rss
• .rtf
• .rw2
• .rwl
• .safe
• .sct
• .sdpx
• .shtm
• .shtml
• .slk
• .sln
• .sql
• .sr2
• .srf
• .srw
• .ssi
• .st
• .stm
• .svg
• .svgz
• .swf
• .tab
• .tar
• .tbb
• .tbi
• .tbk
• .tdi
• .tga
• .thmx
• .tib
• .tif
• .tiff
• .tld
• .torrent
• .tpl
• .txt
• .u3d
• .udl
• .uxdc
• .vault
• .vb
• .vbk
• .vbm
• .vbs
• .vcs
• .vda
• .vdr
• .vdw
• .vdx
• .vhd
• .vib
• .vrp
• .vsd
• .vss
• .vst
• .vsw
• .vsx
• .vtm
• .vtml
• .vtx
• .wav
• .wb2
• .wbm
• .wbmp
• .wim
• .wmf
• .wml
• .wmv
• .wpd
• .wps
• .x3f
• .xl
• .xla
• .xlam
• .xlk
• .xlm
• .xls
• .xlsb
• .xlsm
• .xlsx
• .xlt
• .xltm
• .xltx
• .xlw
• .xml
• .xps
• .xsd
• .xsf
• .xsl
• .xslt
• .xsn
• .xtp
• .xtp2
• .xyze
• .xz
• .zip

It avoids encrypting files with the following strings in their file name:

• desktop.ini
• boot.ini
• Bootfont.bin
• ntuser.ini
• NTUSER.DAT
• IconCache.db

It renames encrypted files using the following names:

• {random characters}.{ID}.crypted000007

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

• {Drive letter}:\README{1-10}.txt
• %Desktop%\README{1-10}.txt

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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