W32.HLLW.Nopadex

Printer Friendly Page

Discovered: November 05, 2002
Updated: February 13, 2007 11:46:25 AM
Type: Worm
Systems Affected: Windows


W32.HLLW.Nopadex is a worm that spreads itself through the KaZaA file-sharing network. It is written in the Microsoft Visual Basic programming language and compressed with tElock. This worm does not have a destructive payload.

Antivirus Protection Dates

  • Initial Rapid Release version November 06, 2002
  • Latest Rapid Release version November 06, 2002
  • Initial Daily Certified version November 06, 2002
  • Latest Daily Certified version November 06, 2002
  • Initial Weekly Certified release date November 06, 2002

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Yana Liu

Discovered: November 05, 2002
Updated: February 13, 2007 11:46:25 AM
Type: Worm
Systems Affected: Windows


When W32.HLLW.Nopadex runs, it does the following:

It creates the C:\%windir%\Win32 folder and copies itself to this folder using the file names that it carries.

NOTE : %windir% is a variable. The worm locates the \Windows folder (by default this is C:\Windows or C:\Winnt) and copies itself to that location.

For example, here are some file names that are used by the worm:

  • Ut2k3 Crack.exe
  • Unreal Tournament 2003 Trainer.exe
  • Awesome Screensaver.exe
  • Weed Screen Saver.exe
  • z1.Av.This.Is.To.exe
  • Kernel32.exe

It adds value

Kernel32 C:\%windir%\Win32\Kernel32.exe

to the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

so that the worm runs when you start Windows.

It also adds the values

dir0 012345:C:\%windir%\Win32
DisableSharing 0

to the registry key

HKEY_CURRENT_USER\Software\Kazaa\LocalContent

so that other KaZaA users can download files from C:\%windir%\Win32.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Yana Liu

Discovered: November 05, 2002
Updated: February 13, 2007 11:46:25 AM
Type: Worm
Systems Affected: Windows


NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Update the virus definitions.
  2. Run a full system scan, and delete all files that are detected as W32.HLLW.Nopadex. Remove the C:\%windir%\Win32 folder.
  3. Delete the value

    Kernel32 C:\%Windir%\Win32\Kernel32.exe

    from the registry key

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  4. Delete the value

    dir0 012345:C:\%windir%\Win32

    from the registry key

    HKEY_CURRENT_USER\Software\Kazaa\LocalContent

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
  • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

    Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

To scan for and delete the infected files:
  1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.HLLW.Nopadex, click Delete.
  4. Using Windows Explorer, delete the folder C:\%windir%\Win32.

To remove the value from the registry:

CAUTION : Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
  1. Click Start, and then click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the following key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, delete the value:

    Kernel32    C:\%windir%\Win32\Kernel32.exe
  5. Navigate to the following key:

    HKEY_CURRENT_USER\Software\Kazaa\LocalContent
  6. In the right pane, delete the value:

    dir0     012345:C:\%windir%\Win32
  7. Click Registry, and click Exit.


Writeup By: Yana Liu