Ransom.MSIL.CHAOS.H

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 adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

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:

• %Application Data%\svchost.exe → if {Malware Path}\{Malware Filename} is not %Application Data%\svchost.exe

(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).)

It drops the following files:

• %User Temp%\{9 random characters}.jpg → Used as wallpaper

(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).)

It adds the following processes:

• %Application Data%\svchost.exe → if {Malware Path}\{Malware Filename} is not %Application Data%\svchost.exe
• "%System%\cmd.exe" /C vssadmin delete shadows /all /quiet & wmic shadowcopy delete
• "%System%\cmd.exe" /C bcdedit /set {default} bootstatus policy ignoreallfailures & bcdedit /set {default} recoveryenabled no
• "%System%\cmd.exe" /C wbadmin delete catalog -quiet
• "%System%\NOTEPAD.EXE" %Application Data%\READ_ME.txt

(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).. %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
UpdateTask = %Application Data%\svchost.exe

Other System Modifications

This Ransomware adds the following registry entries to disable the Task Manager:

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 characters}.jpg

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

• %User Temp%\{9 random characters}.jpg
  

Propagation

This Ransomware drops copies of itself in the following drives:

• {Available Drive aside C:}\surprise.exe

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 adds the following registry keys:

HKEY_CURRENT_USER\Software\oAnWieozQPsRK7Bj83r4

It does the following:

• It encrypts files with file size below 2,170,986,240 bytes.
• It randomly encrypts files with file size above 2,170,986,240 bytes rendering the file unusable.
• 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:

• .txt
• .jar
• .dat
• .contact
• .settings
• .doc
• .docx
• .xls
• .xlsx
• .ppt
• .pptx
• .odt
• .jpg
• .mka
• .mhtml
• .oqy
• .png
• .csv
• .py
• .sql
• .mdb
• .php
• .asp
• .aspx
• .html
• .htm
• .xml
• .psd
• .pdf
• .xla
• .cub
• .dae
• .indd
• .cs
• .mp3
• .mp4
• .dwg
• .zip
• .rar
• .mov
• .rtf
• .bmp
• .mkv
• .avi
• .apk
• .lnk
• .dib
• .dic
• .dif
• .divx
• .iso
• .7zip
• .ace
• .arj
• .bz2
• .cab
• .gzip
• .lzh
• .tar
• .jpeg
• .xz
• .mpeg
• .torrent
• .mpg
• .core
• .pdb
• .ico
• .pas
• .db
• .wmv
• .swf
• .cer
• .bak
• .backup
• .accdb
• .bay
• .p7c
• .exif
• .vss
• .raw
• .m4a
• .wma
• .flv
• .sie
• .sum
• .ibank
• .wallet
• .css
• .js
• .rb
• .crt
• .xlsm
• .xlsb
• .7z
• .cpp
• .java
• .jpe
• .ini
• .blob
• .wps
• .docm
• .wav
• .3gp
• .webm
• .m4v
• .amv
• .m4p
• .svg
• .ods
• .bk
• .vdi
• .vmdk
• .onepkg
• .accde
• .jsp
• .json
• .gif
• .log
• .gz
• .config
• .vb
• .m1v
• .sln
• .pst
• .obj
• .xlam
• .djvu
• .inc
• .cvs
• .dbf
• .tbi
• .wpd
• .dot
• .dotx
• .xltx
• .pptm
• .potx
• .potm
• .pot
• .xlw
• .xps
• .xsd
• .xsf
• .xsl
• .kmz
• .accdr
• .stm
• .accdt
• .ppam
• .pps
• .ppsm
• .1cd
• .3ds
• .3fr
• .3g2
• .accda
• .accdc
• .accdw
• .adp
• .ai
• .ai3
• .ai4
• .ai5
• .ai6
• .ai7
• .ai8
• .arw
• .ascx
• .asm
• .asmx
• .avs
• .bin
• .cfm
• .dbx
• .dcm
• .dcr
• .pict
• .rgbe
• .dwt
• .f4v
• .exr
• .kwm
• .max
• .mda
• .mde
• .mdf
• .mdw
• .mht
• .mpv
• .msg
• .myi
• .nef
• .odc
• .geo
• .swift
• .odm
• .odp
• .oft
• .orf
• .pfx
• .p12
• .pl
• .pls
• .safe
• .tab
• .vbs
• .xlk
• .xlm
• .xlt
• .xltm
• .svgz
• .slk
• .tar.gz
• .dmg
• .ps
• .psb
• .tif
• .rss
• .key
• .vob
• .epsp
• .dc3
• .iff
• .onepkg
• .onetoc2
• .opt
• .p7b
• .pam
• .r3d

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

• READ_ME.txt

It avoids encrypting files found in the following folders:

• In the %System Root%:
  • Program Files
  • Program Files (x86)
  • Windows
  • $Recycle.Bin
  • MSOCache
  • Documents and Settings
  • Intel
  • PerfLogs
  • Windows.old
  • AMD
  • NVIDIA
  • ProgramData

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

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

• .mesmerised

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

• {Encrypted Folder}\READ_ME.txt
• %Application Data%\READ_ME.txt