RANSOM_CRYPSHED.TX

 Analysis by: Julie Anne Cabuhat

 ALIASES:

Ransom:Win32/Ranscrape (Microsoft), Trojan-Ransom.Win32.Shade.lfu (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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.

  TECHNICAL DETAILS

File Size:

940,638 bytes

File Compression:

Nullsoft PiMP SFX

Memory Resident:

No

Initial Samples Received Date:

28 Nov 2016

Payload:

Connects to URLs/IPs, Encrypts files, Renames files, Displays message/message boxes

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 a copy of itself in the following folders using different file names:

  • %ProgramData%\Windows\csrss.exe

(Note: %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.)

Autostart Technique

This Trojan 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 = "%ProgramData%\Windows\csrss.exe"

Other System Modifications

This Trojan adds the following registry keys:

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

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xi = "{ID}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xmode = "{mode}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xstate = "{state}"

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
xcnt = "{encrypted files count}"

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

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
sh2 = "{Public Key}"

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

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\ns{random}.tmp
  • %User Temp%\ns{random}.tmp\System.dll
  • %User Profile%\System32\xfs - list of encrypted files
  • {Drive Letter}:\README{number}.txt-serves as ransom note
  • %User Temp%\metamorph_flash100
  • %User Temp%\jquery-ui-stars_ver-3.9.1.css
  • %User Temp%\button-uqanswers.png
  • %User Temp%\JcyJpqCkpCfIJRU.3mGzJUmd8lt
  • %Application Data%\{random alphanumeric characters}.bmp - wallpaper (serves as ransom notice)

(Note: %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.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %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.)

Other Details

This Trojan encrypts files with the following extensions:

  • .edml
  • .raw
  • .jpg
  • .jpeg
  • .jpe
  • .bmp
  • .png
  • .tif
  • .tiff
  • .dib
  • .gif
  • .svg
  • .svgz
  • .rle
  • .tga
  • .vda
  • .icb
  • .wbm
  • .wbmp
  • .jpf
  • .jpx
  • .jp2
  • .j2k
  • .j2c
  • .jpc
  • .avi
  • .mkv
  • .mov
  • .mp4
  • .wmv
  • .3gp
  • .mpg
  • .mpeg
  • .m4v
  • .divx
  • .mpv
  • .m1v
  • .dat
  • .anim
  • .m4a
  • .qt
  • .3g2
  • .f4v
  • .mkidx
  • .mka
  • .avs
  • .vdr
  • .flv
  • .bin
  • .mp3
  • .wav
  • .asx
  • .pls
  • .zip
  • .7z
  • .rar
  • .tar
  • .gz
  • .bz2
  • .wim
  • .xz
  • .c
  • .h
  • .hpp
  • .cpp
  • .php
  • .php3
  • .php4
  • .php5
  • .py
  • .pl
  • .sln
  • .js
  • .json
  • .inc
  • .sql
  • .java
  • .class
  • .ini
  • .asm
  • .clx
  • .tbb
  • .tbi
  • .tbk
  • .pst
  • .dbx
  • .cbf
  • .crypted
  • .tib
  • .eml
  • .fld
  • .vbm
  • .vbk
  • .vib
  • .vhd
  • .mtr
  • .vault
  • .1cd
  • .dt
  • .cf
  • .cfu
  • .mxl
  • .epf
  • .vrp
  • .grs
  • .geo
  • .elf
  • .lgf
  • .lgp
  • .log
  • .st
  • .pff
  • .mft
  • .efd
  • .md
  • .dmp
  • .fdb
  • .lst
  • .fbk

It renames encrypted files using the following names:

  • {random characters}=.{ID}.no_more_ransom

It sets the attributes of the following file(s) to Hidden and System:

  • %Program Data%\Windows\
  • %User Profile%\System32\
  • %User Profile%\System32\xfs

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It does the following:

  • Deletes Shadow copies
    • %System%\vssadmin.exe Delete Shadows /All /Quiet
  • Installs TOR browser

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

NOTES:

It leaves the following ransom note:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.928.03

FIRST VSAPI PATTERN DATE:

28 Nov 2016

VSAPI OPR PATTERN File:

12.929.00

VSAPI OPR PATTERN Date:

29 Nov 2016

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

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.

 
  • HKEY_LOCAL_MACHINE\SOFTWARE\System32\Configuration

Step 4

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 = "C:\ProgramData\Windows\csrss.exe"

Step 5

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.
  • %User Temp%\ns{random}.tmp
  • %User Temp%\ns{random}.tmp\System.dll
  • %User Profile%\System32\xfs
  • {Drive Letter}:\README{number}.txt
  • %User Temp%\metamorph_flash100
  • %User Temp%\jquery-ui-stars_ver-3.9.1.css
  • %User Temp%\button-uqanswers.png
  • %User Temp%\JcyJpqCkpCfIJRU.3mGzJUmd8lt
  • %Application Data%\{random alphanumeric characters}.bmp

Step 6

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CRYPSHED.TX. 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 7

Restore encrypted files from backup.


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