TROJ_DOFOIL.WYTK

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 is injected into all running processes to remain memory resident.

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:

• %Application Data%\{random folder name}\{random file name}.exe

(Note: %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.)

It creates the following folders:

• %Application Data%\{random folder name}

(Note: %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.)

It is injected into all running processes to remain memory resident.

It injects codes into the following process(es):

• 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
{installed program name} = "%Application Data%\{random folder name}\{random file name}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
{installed program name} = "%Application Data%\{random folder name}\{random file name}.exe"

Dropping Routine

This Trojan drops the following files:

• %Application Data%\{random folder name}\{folder's name} ← config file

(Note: %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.)

Download Routine

This Trojan accesses the following websites to download files:

• http://{BLOCKED}vicekl2.ru/

It downloads a possibly malicious file from a certain URL. The URL where this malware downloads the said file depends on the parameter passed on to it by its components.

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

• http://www.msn.com/

It deletes the initially executed copy of itself

NOTES:

This Trojan connects to the URLs that are found in the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\{Installed Program}
HelpLink = "{url related to installed program}"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\{Installed Program}
URLInfoAbout = "{url related to installed program}"

It perform infinite sleep once it is executed in the following virtual environments:

• sbiedll
• dbghelp
• qemu
• virtual
• vmware
• xen

It looks for the window name Shell_TrayWnd and then opens the process associated with the said window to execute its code. This Trojan does this routine to inject its code to svchost.exe, avoiding HIPS detection.