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RANSOM_CRYPSHED.D

April 18, 2016
 Analysis by: Mar Philip Elaurza
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet


This Trojan may be downloaded by other malware/grayware from remote sites.

It downloads a file from a certain URL then renames it before storing it in the affected system. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

952,832 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Apr 2016

Payload:

Connects to URLs/IPs, Downloads files, Encrypts files, Steals information

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • JS_CRYPSHED.B

Installation

This Trojan 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.)

It drops the following files:

  • %Application Data%\{8 Random Alphanumeric Characters}{Same Characters as first 8}.bmp
  • %User Temp%\cached-certs
  • %User Temp%\cached-microdesc-consensus
  • %User Temp%\cached-microdescs.new
  • %User Temp%\lock
  • %User Temp%\state

(Note: %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.. %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 leaves text files that serve as ransom notes containing the following:

  • {Root Drives}\README{number 1 to 10}.txt
  • %System Root%\Users\Public\Public Desktop\README{number 1 to 10}.txt (Windows Vista and Above)
  • %All Users Profile%\Desktop\README{number 1 to 10}.txt (For Windows XP and Below)
  • %Desktop%\README{number 1 to 10).txt

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 = %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 Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
pk = {PUBLIC KEY}

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
cnt = {numbers}

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
mode = 0

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
state = 5

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
i = {random characters}

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
Version = 7.2.0.3

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
pk = {PUBLIC KEY}

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
cnt = {numbers}

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
mode = 0

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
state = 3

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
i = {random characters}

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
Version = 7.2.0.3

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration
sys = 1

HKEY_CURRENT_USER\SOFTWARE\System32\
Configuration
sys = 1

It modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
wp = "%Application Data%\{random characters}.bmp"

(Note: The default value data of the said registry entry is "{user-defined}".)

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

  • %Application Data%\{8 random alphanumeric characters}{Same characters as first 8}.bmp

Download Routine

This Trojan downloads files from the following URLs then renames them before storage in the affected system:

  • URLs varies based from the list received from the servers

It saves the files it downloads using the following names:

  • %User Temp%\{8 Random Alphanumeric Strings}.exe

(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.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Information Theft

This Trojan gathers the following data:

  • Computer Information
  • Network Information
  • IP Address
  • List of Logical Drives
  • User Name
  • OS Version

Other Details

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

  • whatismyipaddress.com

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

  • http://{server}/{path}

    where {server} can be any of the following:
    • {BLOCKED}.{BLOCKED}.40.189
    • {BLOCKED}.{BLOCKED}.32.5
    • {BLOCKED}.{BLOCKED}.0.39
    • {BLOCKED}.{BLOCKED}.21.38
    • {BLOCKED}.{BLOCKED}.206.212
    • {BLOCKED}.{BLOCKED}.251.203
    • {BLOCKED}.{BLOCKED}.17.194
    • {BLOCKED}.{BLOCKED}.244.244
    • {BLOCKED}.{BLOCKED}.223.34
    • {BLOCKED}.{BLOCKED}.193.9
    • http://{BLOCKED}h2ldj3v.onion
    and where {path} can be any of the following:
    • reg.php
    • prog.php
    • err.php
    • cmd.php
    • sys.php


It 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
  • 1cd
  • dt
  • cf
  • cfu
  • mxl
  • epf
  • vrp
  • grs
  • geo
  • elf
  • lgf
  • lgp
  • log
  • st
  • pff
  • mft
  • efd
  • md
  • dmp
  • fdb
  • lst
  • fbk
  • sw
  • vdw

It renames encrypted files using the following names:

  • {random characters}.better_call_saul
  • {Original File Name}.los_pollos - if filename encryption fails

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.450.06

FIRST VSAPI PATTERN DATE:

06 Apr 2016

VSAPI OPR PATTERN File:

12.451.00

VSAPI OPR PATTERN Date:

07 Apr 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

Remove the malware/grayware file that dropped/downloaded RANSOM_CRYPSHED.D. (Note: Please skip this step if the threat(s) listed below have already been removed.)

Step 4

Restart in Safe Mode

[ Learn More ]

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

Step 6

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
  • In HKEY_CURRENT_USER\SOFTWARE\System32
    • Configuration

Step 7

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.
  • %Application Data%\{8 Random Alphanumeric Characters}{Same Characters as first 8}.bmp
  • %User Temp%\cached-certs
  • %User Temp%\cached-microdesc-consensus
  • %User Temp%\cached-microdescs.new
  • %User Temp%\lock
  • %User Temp%\state
  • {Root Drives}\README{number 1 to 10}.txt
  • %System Root%\Users\Public\Public Desktop\README{number 1 to 10}.txt (Windows Vista and Above)
  • %All Users Profile%\Desktop\README{number 1 to 10}.txt (For Windows XP and Below)
  • %Desktop%\README{number 1 to 10).txt

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPSHED.D. 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 9

Restore encrypted files from backup.

Step 10

Reset your Desktop properties

[ Learn More ]


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