TROJ_CRYPWALL.RUI

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}veloper.com/tmp/b.php
• http://{BLOCKED}la.kz/wp-content/plugins/wp-db-backup-made/a.php
• http://{BLOCKED}h.{BLOCKED}er.com/wp-content/plugins/wp-db-backup-made/b.php
• http://{BLOCKED}digital.com/wp-content/themes/twentytwelve/c.php
• http://{BLOCKED}100unity.com/wp-includes/js/tinymce/skins/wordpress/images/e.php
• http://{BLOCKED}bv.com/plugins/system/plg_system_rewrite/a.php
• http://{BLOCKED}veloper.com/tmp/b.php
• http://{BLOCKED}s.{BLOCKED}ngalore.org/wp-content/themes/twentyeleven/d.php
• http://{BLOCKED}sscod.com/tmp/e.php
• http://{BLOCKED}nadvances.com/wp-content/plugins/updraftplus/oc/guzzle/Guzzle/Service/Command/LocationVisitor/Request/a.php
• http://{BLOCKED}rgical.com/plugins/system/plg_system_rewrite/b.php
• http://{BLOCKED}rymexico.com/foro/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/Session/Storage/Handler/c.php
• http://{BLOCKED}ebetterwe.com/wp-content/plugins/wp-antibot-standart/d.php
• http://{BLOCKED}celets.ro/wp-content/themes/twentytwelve/e.php
• http://{BLOCKED}aonline.com/plugins/system/plg_system_rewrite/a.php
• http://{BLOCKED}el.vn/wp-content/themes/twentytwelve/b.php
• http://{BLOCKED}yroseville.org/wp-content/plugins/wp-antibot-standart/c.php
• http://{BLOCKED}rie.de/wp-content/plugins/revslider/css/jui/new/images/d.php
• http://{BLOCKED}g.{BLOCKED}c.com.pk/wp-content/plugins/wp-antibot-standart/e.php
• http://{BLOCKED}o.de/plugins/system/plg_system_rewrite/a.php
• http://{BLOCKED}cement.com/blog/wp-content/plugins/wp-antibot-standart3/b.php
• http://{BLOCKED}ftball.com/wp-content/themes/sports-team-theme/includes/advanced-custom-fields/assets/inc/datepicker/images/c.php
• http://{BLOCKED}visi.info.tr/wp-content/themes/twentytwelve/d.php
• http://{BLOCKED}k.info/wp-content/uploads/e.php
• http://{BLOCKED}nce.ru/wp-content/themes/dreamynight-10/a.php
• http://{BLOCKED}bahadi.com/wp-content/uploads/b.php
• http://{BLOCKED}lemaneslabardena.com/plugins/system/plg_system_rewrite/c.php
• http://{BLOCKED}zworld.com/wp-content/plugins/wp-antibot-standart/d.php
• http://{BLOCKED}g.{BLOCKED}n.com.br/wp-content/plugins/wp-antibot-standart/a.php
• http://{BLOCKED}homesearch.com/wp-content/plugins/wp-antibot-standart/b.php
• http://{BLOCKED}ic.ro/wp-content/themes/twentytwelve/c.php
• http://{BLOCKED}rwa.com/wp-content/plugins/wp-db-backup-made/a.php
• http://{BLOCKED}g.{BLOCKED}c.uab.es/wordpress/wp-content/plugins/wp-db-backup-made1/d.php
• http://{BLOCKED}lry.com/il/wp-content/plugins/ninja-forms/includes/admin/pages/ninja-forms-settings/tabs/c.php
• http://{BLOCKED}a.com/blog/wp-content/plugins/scribe/lib/history/views/meta-box/c.php
• http://{BLOCKED}n.ru/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/nextgen_gallery_display/templates/list/a.php
• http://{BLOCKED}n.com/wp-content/themes/twentythirteen/e.php
• http://{BLOCKED}es.com/wp-content/themes/twentyeleven/a.php
• http://{BLOCKED}partman.hu/de/wp-content/plugins/wp-db-backup-made/e.php
• http://{BLOCKED}oyunlari.org/wp-content/themes/twentytwelve/b.php
• http://{BLOCKED}magenes.com/wp-content/plugins/wp-mobile-edition/admin/includes/mobile_themes/mTheme-Unus/images/blue/a.php
• http://{BLOCKED}ron.com/wp-content/plugins/contact-form-7/includes/js/jquery-ui/themes/smoothness/images/a.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 URL:

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