RANSOM_CRYPWALL.BYE

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:

• http://{BLOCKED}onbooster.com/wp-content/plugins/e1.php
• http://{BLOCKED}fts.com/blog/wp-content/plugins/e2.php
• {BLOCKED}curacao.info/wp-content/plugins/e3.php
• {BLOCKED}generator.co.uk/wp-content/plugins/e4.php
• {BLOCKED}tersmeyer.com/wp-content/plugins/e1.php
• {BLOCKED}urneighbortour.com/wp-includes/e2.php
• {BLOCKED}ts.com/wp-includes/e3.php
• {BLOCKED}cksusa.com/e4.php
• {BLOCKED}gilbert.com/wp-admin/e1.php
• {BLOCKED}et-tester.com/wp-includes/e2.php
• {BLOCKED}-cards.de/wp-admin/user/e4.php
• {BLOCKED}ooks.com/wp-includes/e5.php
• {BLOCKED}e.com/e1.php
• {BLOCKED}sprado.com.br/wp-includes/e2.php
• {BLOCKED}sprado.net/wp-includes/e3.php
• {BLOCKED}orial.in/wp-content/plugins/slider-image/Front_images/e4.php
• {BLOCKED}o.com/wp-includes/certificates/e5.php
• {BLOCKED}escargas.com/wp-includes/pomo/e1.php
• {BLOCKED}computingtoday.com/wp-content/plugins/contact-form-7/modules/e2.php
• {BLOCKED}freevacations.com/web_admin/files/e3.php
• {BLOCKED}pune.com/web_admin/files/e4.php
• {BLOCKED}perties.com/wp-includes/theme-compat/e5.php
• {BLOCKED}orgeandfitting.in/wp-content/plugins/google-map-shortcode/languages/e1.php
• {BLOCKED}les.com/web_admin/files/e2.php
• {BLOCKED}rm.com/wp-includes/theme-compat/e3.php
• {BLOCKED}tners.com/ktb/wp-includes/theme-compat/e4.php
• {BLOCKED}omix.com/wp-includes/theme-compat/e5.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