Ransom.MSIL.CHAOS.THDAGBD

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 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 files:

• %Application Data%\SOLUTION_NOTE.txt
• %User Temp%\{9 Random Character}.jpg

(Note: %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).. %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).)

It drops and executes the following files:

• %Application Data%\svchost.exe → Executed with Escalated Privileges

(Note: %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).)

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
UpdateTask = %Application Data%\svchost.exe

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\{9 Random Character}.jpg

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

• %User Temp%\{9 Random Character}.jpg
  
  

Propagation

This Ransomware drops the following copy of itself in all physical and removable drives:

• {Drive Letter}:\surprise.exe → Excluding drive C:\

Process Termination

This Ransomware terminates the following services if found on the affected system:

• BackupExecAgentBrowser
• BackupExecDiveciMediaService
• BackupExecJobEngine
• BackupExecManagementService
• vss
• sql
• svc$
• memtas
• sophos
• veeam
• backup
• GxVss
• GxBlr
• GxFWD
• GxCVD
• GxCIMgr
• DefWatch
• ccEvtMgr
• SavRoam
• RTVscan
• QBFCService
• Intuit.QuickBooks.FCS
• YooBackup
• YooIT
• zhudongfangyu
• sophos
• stc_raw_agent
• VSNAPVSS
• QBCFMonitorService
• VeeamTransportSvc
• VeeamDeploymentService
• VeeamNFSSvc
• veeam
• PDVFSService
• BackupExecVSSProvider
• BackupExecAgentAccelerator
• BackupExecRPCService
• AcrSch2Svc
• AcronisAgent
• CASAD2DWebSvc
• CAARCUpdateSvc
• TeamViewer

Other Details

This Ransomware does the following:

• It displays a message box and terminates execution if any of the input languages below is detected:
  • Azerbaijan
  • Turkey
  
  

Ransomware Routine

This Ransomware encrypts files with the following extensions:

• .aac
• .adt
• .adts
• .accdb
• .accde
• .accdr
• .accdt
• .aif
• .aifc
• .aiff
• .aspx
• .avi
• .bat
• .bin
• .bmp
• .cab
• .cda
• .csv
• .dif
• .dll
• .doc
• .docm
• .docx
• .dot
• .dotx
• .eml
• .eps
• .exe
• .flv
• .gif
• .htm
• .html
• .ini
• .iso
• .jar
• .jpg
• .jpeg
• .m4a
• .mdb
• .mid
• .midi
• .mov
• .mp3
• .mp4
• .mpeg
• .mpg
• .msi
• .mui
• .pdf
• .png
• .pot
• .potm
• .potx
• .ppam
• .pps
• .ppsm
• .ppsx
• .ppt
• .pptm
• .pptx
• .psd
• .pst
• .pub
• .rar
• .rtf
• .sldm
• .sldx
• .swf
• .sys
• .tif
• .tiff
• .tmp
• .txt
• .vob
• .vsd
• .vsdm
• .vsdx
• .vss
• .vst
• .vstm
• .wav
• .wbk
• .wks
• .wma
• .wmd
• .wmv
• .wmz
• .wms
• .wpd
• .wp5
• .xla
• .xlam
• .xll
• .xlm
• .xls
• .xlsm
• .xlt
• .xltm
• .xltx
• .xps
• .zip
• .au
• .class
• .cvs
• .dbf
• .fm3
• .hqx
• .mac
• .map
• .mtb
• .psp
• .qxd
• .ra
• .sit
• .tar
• .wk3
• .wpl
• .7z
• .arj
• .deb
• .pkg
• .rpm
• .tar.gz
• .z
• .dmg
• .toast
• .vcd
• .dat
• .db
• .log
• .sav
• .sql
• .xml
• .email
• .emlx
• .msg
• .oft
• .ost
• .vcf
• .gadget
• .sh
• .wsf
• .fnt
• .fon
• .otf
• .ttf
• .ai
• .ico
• .ps
• .scr
• .svg
• .webp
• .asp
• .cer
• .cfm
• .css
• .jsp
• .part
• .php
• .py
• .rss
• .xhtml
• .key
• .odp
• .apk
• .c
• .cpp
• .cs
• .h
• .java
• .swift
• .vb
• .ods
• .bak
• .cfg
• .cpl
• .cur
• .dmp
• .drv
• .icns
• .lnk
• .3g2
• .3gp
• .h264
• .m4v
• .mkv
• .rm
• .webm
• .contact
• .settings
• .xlsx
• .odt
• .mka
• .mhtml
• .oqy
• .mdb
• .cub
• .dae
• .indd
• .dwg
• .lnk
• .dib
• .dic
• .divx
• .7zip
• .ace
• .bz2
• .cab
• .gzip
• .lzh
• .xz
• .torrent
• .core
• .pdb
• .wmv
• .cer
• .backup
• .bay
• .p7c
• .exif
• .raw
• .sie
• .sum
• .ibank
• .wallet
• .rb
• .xlsm
• .xlsb
• .jpe
• .blob
• .xlw
• .xsd
• .xsf
• .xsl
• .kmz
• .stm
• .accdt
• .1cd
• .3fr
• .adp
• .ai3
• .ai4
• .ai5
• .ai6
• .ai7
• .ai8
• .arw
• .ascx
• .asm
• .asmx
• .avs
• .cfm
• .dbx
• .dcm
• .dcr
• .pict
• .rgbe
• .dwt
• .f4v
• .exr
• .kwm
• .max
• .mda
• .mdf
• .mdw
• .mht
• .mpv
• .myi
• .nef
• .odc
• .geo
• .odm
• .oft
• .orf
• .pfx
• .p12
• .pl
• .pls
• .safe
• .tab
• .vbs
• .xlk
• .xlm
• .xltx
• .pptx
• .pot
• .xps
• .xsf
• .xsl
• .pptm
• .potm
• .xltx
• .pptm
• .potm
• .pot
• .xlw
• .kmz
• .accdr
• .accdw
• .acda
• .accdc
• .accdw
• .bin
• .ascx
• .asm
• .asmx
• .avs
• .cfm
• .dbx
• .dcm
• .dcr
• .rgbe
• .f4v
• .exr
• .kwm
• .max
• .mda
• .mdf
• .mdw
• .mht
• .mpv
• .myi
• .nef
• .odc
• .geo
• .odm
• .orf
• .pfx
• .p12
• .pl
• .pls
• .safe
• .tab
• .vbs
• .xlk
• .xlm
• .xlt
• .pptm
• .potm
• .xltx
• .xps
• .xsf
• .xsl
• .pptm
• .potm
• .xltx

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

• boot.ini
• bootfont.bin
• boot.ini
• iconcache.db
• ntuser.dat
• ntuser.dat.log
• ntuser.ini
• thumbs.db
• autorun.inf
• bootsect.bak
• desktop.ini

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

• appdata\local
• appdata\locallow
• users\all users
• \ProgramData

It avoids encrypting files found in the following folders:

• In Drive C, it will avoid the following directories:
  • %User Profile%\Desktop
  • %User Profile%\Links
  • %User Profile%\Contacts
  • %User Profile%\Desktop
  • %User Profile%\Documents
  • %User Profile%\Downloads
  • %User Profile%\Pictures
  • %User Profile%\Music
  • %User Profile%\OneDrive
  • %User Profile%\Saved Games
  • %User Profile%\Favorites
  • %User Profile%\Searches
  • %User Profile%\Videos
  • %User Profile%\AppData\Roaming
  • %Public%\Documents
  • %Public%\Pictures
  • %Public%\Music
  • %Public%\Videos
  • %Public%\Desktop

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

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

• .LethalLock

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

• {Encrypted Directory\SOLUTION_NOTE.txt