TROJ_CRYPTWALL.YYY

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

(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.)

It creates the following folders:

• %System Root%\{Random 8 Characters}

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

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 8 Characters} = "%Application Data%\{Random 8 Characters}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{First 7 Characters of {Random 8 Characters}} = "%System Root%\{Random 8 Characters}\{Random 8 Characters}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*{Second to the Sixth Characters {Random 8 Characters}} = "%System Root%\{Random 8 Characters}\{Random 8 Characters}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*{Last Seven Characters of {Random 8 Characters}} = "%Application Data%\{Random 8 Characters}.exe"

It drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:

• %User Startup%\{Random 8 Characters}.exe

(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.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{random string}

HKEY_CURRENT_USER\Software\{random string}\
{random string 2}

It adds the following registry entries:

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

HKEY_CURRENT_USER\Software\{random string}
{random string 2} = "[DEFAULT]BASEURL={data} [InternetShortcut]={data}"

HKEY_CURRENT_USER\Software\{random string}
{random string 2} = "{hex value}"

Other Details

This Trojan connects to the following possibly malicious URL:

• {BLOCKED}icalhealthservices.com.au/wp-content/wp-content/plugins/aa.php
• {BLOCKED}m.com.au/wp-content/plugins/bb.php
• {BLOCKED}m.com/wp-content/themes/cc.php
• {BLOCKED}ages.com/wp-content/themes/dd.php
• {BLOCKED}arabulut.com/wp-content/plugins/aa.php
• {BLOCKED}referralnetwork.com/wp-content/plugins/bb.php
• {BLOCKED}velblog.com/wp-content/themes/cc.php
• {BLOCKED}aboca.com/wp-content/themes/dd.php
• {BLOCKED}sta.com/wp-content/themes/ee.php
• {BLOCKED}edreaming.com/wp-content/themes/aa.php
• {BLOCKED}ds.com/wp-content/plugins/bb.php
• {BLOCKED}ncerswap.com/wp-content/plugins/cc.php
• {BLOCKED}admatters.com/wp-content/themes/dd.php
• {BLOCKED}box.com/wp-content/themes/ee.php
• {BLOCKED}uctsinc.com/wp-content/plugins/aa.php
• {BLOCKED}x.com/wp-content/plugins/bb.php
• {BLOCKED}akeupartists.com/wp-content/plugins/bb.php
• {BLOCKED}man.com/wp-content/plugins/cc.php
• {BLOCKED}tical.com/wp-content/plugins/dd.php
• {BLOCKED}promoworks.com/wp-content/plugins/ee.php
• {BLOCKED}rspeaking.com/wp-content/themes/aa.php
• {BLOCKED}irts.com/wp-content/plugins/bb.php
• {BLOCKED}s.com/wp-content/themes/cc.php
• {BLOCKED}de-blah.com/wp-content/plugins/dd.php
• {BLOCKED}n.com/wp-content/themes/ee.php
• {BLOCKED}klechoppers.com/wp-content/plugins/aa.php
• {BLOCKED}x.com/wp-content/plugins/bb.php
• {BLOCKED}sd.com/wp-content/plugins/cc.php
• {BLOCKED}der.com/wp-content/plugins/dd.php
• {BLOCKED}larose.com/wp-content/plugins/ee.php
• {BLOCKED}oersam.com/wp-content/plugins/aa.php
• {BLOCKED}tapreppersparadise.com/wp-content/plugins/bb.php
• {BLOCKED}argenutrition.com/wp-content/plugins/cc.php
• {BLOCKED}abbitartdesign.com/wp-content/plugins/dd.php
• {BLOCKED}peone.com/wp-content/plugins/ee.php
• {BLOCKED}nd.com/wp-content/plugins/aa.php
• {BLOCKED}erynature.com/wp-content/plugins/bb.php
• {BLOCKED}x.com/wp-content/plugins/cc.php
• {BLOCKED}blend.com/wp-content/themes/dd.php
• {BLOCKED}bontubes.com/wp-content/plugins/ee.php
• {BLOCKED}qvarnamowers.com/wp-content/themes/aa.php
• {BLOCKED}nc.com/wp-content/plugins/bb.php
• {BLOCKED}r.es

It deletes the initially executed copy of itself

NOTES:

This Trojan is capable of encrypting files in the affected system.

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