TROJ_CRYPWALL

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 adds the following folders:

• %System Root%\{7 characters from UID}

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

It drops the following files:

• %User Startup%\DECRYPT_INSTRUCTION.TXT
• %User Startup%\DECRYPT_INSTRUCTION.HTML
• %User Startup%\INSTALL_TOR.URL

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

It drops and executes the following files:

• %Desktop%\DECRYPT_INSTRUCTION.TXT
• %Desktop%\DECRYPT_INSTRUCTION.HTML
• %Desktop%\INSTALL_TOR.URL

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop 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.)

It drops the following copies of itself into the affected system:

• %System Root%\{7 characters from UID}\{7 characters from UID}.exe
• %Application Data%\{7 characters from UID}.exe
• %User Startup%\{7 characters from UID}.exe

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %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 Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

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
{7characters from UID} = "%Application Data%\{7 characters from UID}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{6 characters from UID} = "%System Root%\{7 characters from UID}\{7 characters from UID}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Vocal AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Vocal AppWizard-Generated Applications\
{random}

HKEY_CURRENT_USER\Software\Vocal AppWizard-Generated Applications\
{random}\Recent File List

HKEY_CURRENT_USER\Software\Vocal AppWizard-Generated Applications\
{random}\Settings

Other Details

This Trojan connects to the following website to send and receive information:

• http://www.{BLOCKED}apmak.com/{random value}
• http://www.{BLOCKED}tringen.de/wordpress/{random value}
• http://www.{BLOCKED}psphotography.co.uk/blog/{random value}
• http://www.{BLOCKED}nguild.com/{random value}
• http://www.{BLOCKED}e.be/{random value}
• http://www.{BLOCKED}-schwarzenberg.de/wp-content/themes/fdp-asz/{random value}
• http://www.{BLOCKED}ntiques.co.uk/blog/{random value}
• http://www.{BLOCKED}erburg.ch/wordpress/{random value}
• http://www.{BLOCKED}info.com/wp-content/themes/mh/{random value}
• http://www.{BLOCKED}ifesupport.com/{random value}
• http://eportfolio.{BLOCKED}man.ca/blog/{random value}
• http://www.{BLOCKED}man.com/wp-content/themes/s431_Blue/{random value}
• http://{BLOCKED}tner.cz/{random value}
• http://www.{BLOCKED}mann.de/{random value}
• http://www.{BLOCKED}rda.com/blog-trabajos/{random value}
• http://www.{BLOCKED}r.at/jesneu/wp-content/themes/Girl/{random value}
• http://www.{BLOCKED}rideal.com.br/site/{random value}
• http://www.{BLOCKED}mes.com/{random value}

It encrypts files with the following extensions:

• .pdf
• .pdf
• .pot
• .pot
• .hta
• .xlt
• .xlt
• .pps
• .pps
• .xlw
• .xlw
• .dot
• .dot
• .rtf
• .rtf
• .ppt
• .ppt
• .xls
• .xls
• .doc
• .doc
• .xml
• .xml
• .htm
• .htm
• .html
• .html
• .hta
• .zip
• .dvr-ms
• .wvx
• .wmx
• .wmv
• .wm
• .mpv2
• .mpg
• .mpeg
• .mpe
• .mpa
• .mp2v
• .mp2
• .m1v
• .IVF
• .asx
• .asf
• .wax
• .snd
• .rmi
• .m3u
• .au
• .aiff
• .aifc
• .aif
• .midi
• .mid
• .wma
• .wav
• .mp3
• .wmf
• .tiff
• .tif
• .rle
• .png
• .jpeg
• .jpe
• .jpg
• .jfif
• .ico
• .gif
• .emf
• .dib
• .bmp

NOTES:

TROJ_CRYPWALL usually drops the following files in all folders where files are encrypted:

• DECRYPT_INSTRUCTION.TXT
• DECRYPT_INSTRUCTION.HTML
• INSTALL_TOR.URL

It opens the following ransom note DECRYPT_INSTRUCTION.HTML, which it also drops:

It demands payment for using decryption services:

It deletes shadow copies by executing the following command:

vssadmin.exe Delete Shadows /All /Quiet