BKDR_SHOTODOR.TL

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

It executes commands from a remote malicious user, effectively compromising the affected system.

It terminates if the said processes exist. This is to ensure that it runs uninterrupted on the affected system.

Arrival Details

This backdoor 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 backdoor drops the following files:

• {Script path}\run.vbs
• %User Profile%\945nt9197sbll\check.txt

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It injects itself into the following processes running in the affected system's memory:

• RegSvcs.exe
• RegAsm.exe
• AppLaunch.exe
• RegSvcs.exe
• RegAsm.exe
• AppLaunch.exe
• newdev.exe
• twunk_32.exe
• ndadmin.exe

It creates the following folders:

• %User Profile%\945nt9197sbll

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• Adobe.exe

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER64\Software\Microsoft\
Windows\CurrentVersion\RunOnce
945nt9197sbll = "%User Profile%\945nt9197sbll\98358.vbs"

It drops the following files:

• %User Profile%\945nt9197sbll\97154.cmd - batch file to execute the malware script
• %User Profile%\945nt9197sbll\98358.vbs - vbscript file to execute the dropped batch file

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

• %Start Menu%\start.lnk

(Note: %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE64\Software\Microsoft\
Windows NT\CurrentVersion\SPP\
Clients

It modifies the following registry entries:

HKEY_LOCAL_MACHINE64\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = 0

(Note: The default value data of the said registry entry is "1".)

It adds the following registry entries to disable the Task Manager:

HKEY_CURRENT_USER64\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

(Note: The default value data of the said registry entry is "0".)

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_CURRENT_USER64\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = 1

(Note: The default value data of the said registry entry is "0".)

HKEY_CURRENT_USER64\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is "1".)

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

• Delete all files in %Start Menu%
• Delete all registry entries in:
  HKCU64\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  HKCU64\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  HKLM64\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  HKLM64\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
• Download files
• Log keystrokes
• Manipulate the following to send messages:
  
  • Skype
  • Facebook
  • Steam
  • Omegle
  • TinyChat
  • RunEscape

(Note: %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

Other Details

This backdoor checks for the presence of the following process(es):

• VboxService.exe
• VMwaretray.exe

It terminates if the said processes exist. This is to ensure that it runs uninterrupted on the affected system.

NOTES:

It sets the attribute of following folders to System, Read Only and Hidden to prevent users from discovering and removing its components:

• {Script path}

It checks for the process and terminate itself if said process contains the following string:

• Program Manager