RANSOM_CRYPSHED.THBOAH

 Analysis by: Noel Anthony Llimos

 ALIASES:

Trojan-Ransom.Win32.Shade.ono (Kaspersky), Ransom.Troldesh (Norton), Ransom:Win32/Troldesh.A (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware

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.

  TECHNICAL DETAILS

File Size:

954,600 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

01 Feb 2018

Payload:

Drops files, Connects to URLs/IPs

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:

  • %All Users Profile%\Application Data\Windows\csrss.exe (Windows XP and below)
  • %All Users Profile%\Windows\csrss.exe (Windows Vista and above)
  • %ProgramData%\System32\xfs (Hidden) --- List of all the Encrypted Files of the Victim
  • {Drive Letter}:\README{1-10}.txt --- Ransom Note
  • {Folder Containing Encrypted Files}\README.txt --- Ransom Note
  • %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

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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 Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

It 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 All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 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%\Windows\csrss.exe {Windows Vista and above}

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

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
xi = {Random}

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
sh1 = "{number}"

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

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 does the following:

  • Installs TOR Browser
  • It deletes shadow copies by executing the following commands:
    • %System%\vssadmin.exe Delete Shadows /All /Quiet
  • 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

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

      • {Random Characters}=.{ID}.crypted000007

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.942.02

FIRST VSAPI PATTERN DATE:

31 Jan 2018

VSAPI OPR PATTERN File:

13.943.00

VSAPI OPR PATTERN Date:

01 Feb 2018

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

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\Software\System32\Configuration
    • xVersion = 4.0.0.1
  • In HKEY_LOCAL_MACHINE\Software\System32\Configuration
    • xi = {Random}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • xpk = "{PUBLIC KEY}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • xmode = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • xi = "{Random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • xstate = {number}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • xcnt = "{number}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • shsnt = "{number}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • sh1 = "{number}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration
    • sh2 = "{number}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\System32
    • Configuration

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Client Server Runtime Subsystem = %All Users Profile%\Windows\csrss.exe {Windows Vista and above}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Client Server Runtime Subsystem = %All Users Profile%\Application Data\Windows\csrss.exe (Windows XP and below)

Step 6

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.
  • %All Users Profile%\Application Data\Windows\csrss.exe (Windows XP and below)
  • %All Users Profile%\Windows\csrss.exe (Windows Vista and above)
  • %ProgramData%\System32\xfs (Hidden) --- List of all the Encrypted Files of the Victim
  • {Drive Letter}:\README{1-10}.txt --- Ransom Note
  • {Folder Containing Encrypted Files}\README.txt --- Ransom Note
  • %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
  • %All Users Profile%\Application Data\Windows\csrss.exe (Windows XP and below)
  • %All Users Profile%\Windows\csrss.exe (Windows Vista and above)

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPSHED.THBOAH. 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 8

Restore encrypted files from backup.

Step 9

Reset your Desktop properties

[ Learn More ]


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