RANSOM_CRYPWALL.CPC

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 deletes the initially executed copy of itself.

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:

• %System Root%\{random 8 characters}\{random 8 characters}.exe
• %Application Data%\{random 8 characters}.exe
• %User Startup%\{random 8 characters}.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:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

It drops the following files:

• %Desktop%\HELP_DECRYPT.HTML
• %Desktop%\HELP_DECRYPT.PNG
• %Desktop%\HELP_DECRYPT.TXT
• %Desktop%\HELP_DECRYPT.URL
• %User Startup%\HELP_DECRYPT.HTML
• %User Startup%\HELP_DECRYPT.PNG
• %User Startup%\HELP_DECRYPT.TXT
• %User Startup%\HELP_DECRYPT.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.. %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

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
{random 7 characters} = "%System Root%\{random 8 characters}\{random 8 characters}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random 8 characters} = "%Application Data%\{random 8 characters}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{UID}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{UID}
{random 2 characters} = "{RSA PUBLIC KEY} "

HKEY_CURRENT_USER\Software\{UID}
{random 2 characters} = "{contents of HELP_DECRYPT.TXT}"

HKEY_CURRENT_USER\Software\{UID}
{random 2 characters} = "{contents of HELP_DECRYPT.HTML}"

HKEY_CURRENT_USER\Software\{UID}
{random 2 characters} = "{contents of HELP_DECRYPT.URL}"

HKEY_CURRENT_USER\Software\{UID}\
{random key}
{Path and file of encrypted file} = "{hex values}"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ERSvc
Start = "4"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc
Start = "4"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\BITS
Start = "4"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
Start = "4"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"

(Note: The default value data of the said registry entry is 0.)

Other Details

This Trojan connects to the following possibly malicious URL:

• {BLOCKED}form.com.sg/staging/wp-includes/aa.php
• {BLOCKED}solutions.com/wp-includes/js/tinymce/themes/advanced/skins/o2k7/img/dd.php
• {BLOCKED}-jones.co.nz/wp-includes/js/tinymce/plugins/aa.php
• {BLOCKED}nc.com/wp-content/plugins/bb.php
• {BLOCKED}potolkov12.ru/wp-content/plugins/cc.php
• {BLOCKED}immer.nl/wp-content/themes/dd.php
• {BLOCKED}atone.com/wp-content/plugins/aa.php
• {BLOCKED}international.com/sgsbeautify.com/wp-content/bb.php
• {BLOCKED}ic.co.za/cc.php
• {BLOCKED}u.co.uk/wp-includes/dd.php
• {BLOCKED}girlphotography.com/wp-includes/ee.php
• {BLOCKED}smilesofhamden.com/wp-content/aa.php
• {BLOCKED}4.com/news3/wp-includes/bb.php
• {BLOCKED}illiams.com.au/wp-content/cc.php
• {BLOCKED}-central.de/piwik/core/Tracker/Db/Pdo/dd.php
• {BLOCKED}ion.co.uk/wp-content/uploads/2015/03/update-a9afa977161aa75fe3a7b760b1051876/tmp/ee.php
• {BLOCKED}xp.com/starcraft2guides/wp-content/plugins/aa.php
• freetrial.{BLOCKED}nline.com/wp-content/plugins/bb.php
• {BLOCKED}uresandtrips.com/wp-content/plugins/cc.php
• {BLOCKED}redservices.org.uk/wp-content/plugins/dd.php
• {BLOCKED}esschoolcentral.org/dir/wp-content/ee.php
• {BLOCKED}nmasonry.com/wp-includes/aa.php
• {BLOCKED}a-biografikwn.com/wp-content/plugins/bb.php
• {BLOCKED}rsscandal.com/wp-content/themes/cc.php
• {BLOCKED}uadalajara.org/wp-content/plugins/dd.php
• {BLOCKED} -healthcare-management-for-leaders.com/bemerkenswert/wp-content/ee.php
• {BLOCKED}form.com.sg/staging/wp-includes/aa.php
• pulse.{BLOCKED}z.com/wp-content/uploads/updatedmaps/Arvada/Old%20Arvada/bb.php
• {BLOCKED}viciossas.net/wp-includes/cc.php
• www.{BLOCKED}anty.com/wp-content/themes/dd.php
• {BLOCKED}estorationpros.com/wp-content/plugins/ee.php
• {BLOCKED}as.net/wp-content/plugins/bb.php
• blog.{BLOCKED}iprzyszlosc.pl/wp-includes/js/tinymce/plugins/cc.php
• {BLOCKED}solutions.com/wp-includes/js/tinymce/themes/advanced/skins/o2k7/img/dd.php
• {BLOCKED}o.com/wp-content/plugins/woocommerce-one-click/vendor/stripe/stripe-php/lib/Error/ee.php
• {BLOCKED}og.co.za/aa.php

It deletes the initially executed copy of itself

NOTES:

It drops HELP_DECRYPT.HTML, HELP_DECRYPT.PNG, HELP_DECRYPT.TXT, and HELP_DECRYPT.URL to all folders where files are encrypted.

It connects to the following non-malicious URLs:

• http://ip-addr.es
• http://myexternalip.com/raw
• http://curlmyip.com