TROJ_CRYPCTB.YWE

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.

It connects to certain websites to send and receive information.

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 the following copies of itself into the affected system and executes them:

• %User Temp%\{random filename}.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 drops the following files:

• %ProgramData%\{randomly selected folder}\{random filename} (Windows Vista and above)
• %All Users Profile%\Application Data\{randomly selected folder}\{random filename} (Windows XP and below)
• %All Users Profile%\{random filename}.html (Windows Vista and above)
• %ProgramData%\{random filename}.html (Windows Vista and above)
• %All Users Profile%\Application Data\{random filename}.html (Windows XP and below)
• %User Profile%\Documents\!Decrypt-All-Files-{random 7 characters}.bmp (Windows Vista and above)
• %User Profile%\My Documents\!Decrypt-All-Files-{random 7 characters}.bmp (Windows XP and below)
• %User Profile%\Documents\!Decrypt-All-Files-{random 7 characters}.txt (Windows Vista and above)
• %User Profile%\My Documents\!Decrypt-All-Files-{random 7 characters}.txt (Windows XP and below)

(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.. %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.. %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 injects codes into the following process(es):

• svchost.exe

Autostart Technique

This Trojan drops the following files:

• %System%\Tasks\{random filename} (Windows Vista and above)
• %Windows%\Tasks\{random filename}.job (Windows XP and below)

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

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Profile%\{My Documents or Documents}\!Decrypt-All-Files-{random 7 characters}.bmp

(Note: The default value data of the said registry entry is {User Defined}.)

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

(Note: The default value data of the said registry entry is "User Defined".)

HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"

(Note: The default value data of the said registry entry is "User Defined".)

Other Details

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

• http://ip.telize.com

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

• http://{BLOCKED}4qk625n6.onion.lt
• http://{BLOCKED}4qk625n6.onion.gq
• http://{BLOCKED}4qk625n6.tor2web.fi
• http://{BLOCKED}4qk625n6.tor2web.org
• http://{BLOCKED}4qk625n6.tor2web.blutmagie.de
• http://{BLOCKED}4qk625n6.onion.cab

It encrypts files with the following extensions:

• 3fr
• 7z
• accdb
• ai
• arw
• bas
• bay
• blend
• cdr
• cer
• cpp
• cr2
• crt
• c
• crw
• cs
• db
• dbf
• dcr
• dds
• dd
• der
• dng
• docm
• docx
• doc
• dwg
• dxf
• dxg
• eps
• erf
• groups
• indd
• jpe
• jpeg
• jpg
• js
• kdc
• kwm
• mdb
• mdf
• md
• mef
• mrw
• nef
• nrw
• odb
• odm
• odp
• ods
• odt
• orf
• p12
• p7b
• p7c
• pdd
• pdf
• pef
• pem
• pfx
• php
• pl
• pptm
• ppt
• pptx
• psd
• pst
• ptx
• pwm
• py
• r3d
• raf
• rar
• raw
• rtf
• rw2
• rwl
• safe
• sql
• srf
• srw
• txt
• vsd
• wb2
• wpd
• wps
• xlk
• xlsm
• xls
• xlsb
• xlsx
• zip

It renames encrypted files using the following names:

• {original file name and extension}.{random 7 characters}

NOTES:

This Trojan drops the following to all folders where files are encrypted:

• !Decrypt-All-Files-{random 7 characters}.txt
• !Decrypt-All-Files-{random 7 characters}.bmp

The dropped !Decrypt-All-Files-{random 7 letters}.tx contains the following ransom message:

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

It displays the following ransom message: The ransom message can be viewed in 7 different languages: French, Spanish, Austrian, German, Dutch, Italian and English

It allows the user to decrypt up to five files for free:

It asks the user to pay via Bitcoin payment:

If the connection is not established, it will instruct the user on how to pay the ransom in another computer with an internet connection.

It deletes copies of itself and its scheduled task after the time expired.