Threat Encyclopedia

This malware spams messages to users using Skype in order to propagate. The spammed messages contain links that lead to an automatic download of the malware itself. This malware also has backdoor routines, which compromises an affected system's security.

To get a one-glance comprehensive view of the behavior of this Worm, refer to the Threat Diagram shown below.

For the related story, you may read the blog post Shylock Not the Lone Threat Targeting Skype

This worm arrives as attachment to mass-mailed email messages. It arrives via removable drives.

It connects to Internet Relay Chat (IRC) servers. It executes commands from a remote malicious user, effectively compromising the affected system.

It deletes itself after execution.

Arrival Details

This worm arrives as attachment to mass-mailed email messages.

It arrives via removable drives.

Installation

This worm drops the following copies of itself into the affected system and executes them:

• %User Profile%\6489672321067478425\winsvc.exe

(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:

• g4u5f3dg4f

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Windows Update = "%User Profile%\6489672321067478425\winsvc.exe"

Other System Modifications

This worm creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\6489672321067478425\winsvc.exe = "%User Profile%\6489672321067478425\winsvc.exe*:Enabled:Microsoft Windows Update"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

• {drive letter}:\843921.exe

Backdoor Routine

This worm connects to any of the following Internet Relay Chat (IRC) servers:

• {BLOCKED}50.asia
• {BLOCKED}50.in
• {BLOCKED}50.pro

It joins any of the following IRC channel(s):

• #go

It executes the following commands from a remote malicious user:

• Download and execute arbitrary files

As of this writing, the said servers are currently inaccessible.

Download Routine

This worm saves the files it downloads using the following names:

• %Application Data%\winsvcns.sys

(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.)

Other Details

This worm deletes itself after execution.

NOTES:

This worm creates .LNK (shortcut) files pointing to {drive letter}:\843921.exe in all removable drives using the folder names found in the removable drives.

It then hides the said folders.

This worm sends email messages containing a copy of itself as an attachment.

This worm queries the following mail server to harvest email addresses:

• gmx.com

The email it sends out has the following characteristics:

• Uses the following display names:
  
  Anthony
  Barbara
  Betty
  Brian
  Carol
  Charles
  Christopher
  Daniel
  David
  Deborah
  Donald
  Donna
  Dorothy
  Edward
  Elizabeth
  George
  Helen
  James
  Jason
  Jennifer
  Joseph
  Karen
  Kenneth
  Kevin
  Kimberly
  Laura
  Linda
  Margaret
  Maria
  Michael
  Michelle
  Nancy
  Patricia
  Richard
  Robert
  Ronald
  Sandra
  Sarah
  Sharon
  Steven
  Susan
  Thomas
  William
  
• Subject:
  
  Is this you??
  Picture of you???
  Tell me what you think of this picture
  This is the funniest picture ever!
  I cant believe I still have this picture
  Someone showed me your picture
  Your photo isn't really that great
  I love your picture!
  What you think of my new hair color?
  What do you think of my new hair?
  You look so beautiful on this picture
  You should take a look at this picture
  Take a look at my new picture please
  What you think of this picture?
  Should I upload this picture on facebook?
  Someone told me it's your picture
  
• Body:
  
  hahaha
  ;)
  :D
  :P
  :)
  LOL
  ;D

It uses the following file name for its attachment:

• IMG{random number}-JPG.zip

It does not have rootkit capabilities.

It does not exploit any vulnerability.