TROJ_CRYPWALL.VW

This Trojan drops DECRYPT_INSTRUCTION.TXT, DECRYPT_INSTRUCTION.HTML, and DECRYPT_INSTRUCTION.URL to all folders after encryption.

It encrypts Database, Web, Office, Video, Images, Scripts, Text and other non-binary files.

It opens the dropped file DECRYPT_INSTRUCTION.TXT, which contains the ransom note:

The link of the page for the instructions is no longer accessible.

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 modifies the Internet Explorer Zone Settings.

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 drops the following files:

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

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.. %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 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 root folder, which is usually C:\. It is also where the operating system is located.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %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 creates the following folders:

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

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It injects itself into the following processes as part of its memory residency routine:

• svchost.exe

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
{6 characters from UID} = "%System Root%{7 characters from UID}\{7 characters from UID}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{7characters from UID} = "%Application Data%\{7 characters from UID}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{UID}

HKEY_CURRENT_USER\Software\{UID}\
CRYPTLIST

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{UID}\
CRYPTLIST\{Path of encrypted file}
{Filename of encrypted file} = ""

It modifies the following registry entries:

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

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

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

• http:\{BLOCKED}sehri.com\{random alphanumeric characters}
• http:\{BLOCKED}001.com\{random alphanumeric characters}
• http:\{BLOCKED}il.org\{random alphanumeric characters}
• http:\{BLOCKED}119.com\{random alphanumeric characters}
• http:\{BLOCKED}nlunming.com\{random alphanumeric characters}
• http:\{BLOCKED}-house.com\{random alphanumeric characters}
• http:\{BLOCKED}ct.lviv.ua\{random alphanumeric characters}
• http:\{BLOCKED}rgos.com\{random alphanumeric characters}
• http:\{BLOCKED}u.mamgou.net\{random alphanumeric characters}
• http:\{BLOCKED}n-northwan.com\{random alphanumeric characters}
• http:\{BLOCKED}ir.com\{random alphanumeric characters}
• http:\{BLOCKED}lromania.ro\{random alphanumeric characters}
• http:\{BLOCKED}akim.org\{random alphanumeric characters}
• http:\{BLOCKED}awydaniu.com.pl\{random alphanumeric characters}
• http:\{BLOCKED}hanelouis.com\{random alphanumeric characters}
• http:\{BLOCKED}offman.com\{random alphanumeric characters}
• http:\{BLOCKED}ansportation.com\{random alphanumeric characters}
• http:\{BLOCKED}ces-au-chateau.fr\{random alphanumeric characters}
• http:\{BLOCKED}ar24.cz\{random alphanumeric characters}
• http:\{BLOCKED}yip.com\{random alphanumeric characters}