Discovered: February 04, 2002
Updated: February 13, 2007 11:52:26 AM
Type: Trojan Horse


When this Trojan is executed, it displays the following message:

Would you like to be protected from the virus?

Whether you click Yes or No, the Trojan does the following:

The Trojan deletes the file \Windows\Nosystem.exe.

Antivirus Protection Dates

  • Initial Rapid Release version February 05, 2002
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version February 05, 2002
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date February 06, 2002

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

Writeup By: Gor Nazaryan

Discovered: February 04, 2002
Updated: February 13, 2007 11:52:26 AM
Type: Trojan Horse


It then searches for the following files in the \Windows folder:

  • Winhlp32.exe
  • HH.exe

If it finds those files, it then looks in the \Windows folder for these files:
  • Winhlp32.vir
  • Hh.vir

If the Trojan finds them, it deletes the two files with the .exe extension, and renames the files with the .vir extension so that they now have an .exe extension.

NOTE: The .vir extension files may be backup copies of infected files that were created by an antivirus program before the program attempted to repair an infected file.

The Trojan then changes your Internet Explorer home page to blank.

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: Gor Nazaryan

Discovered: February 04, 2002
Updated: February 13, 2007 11:52:26 AM
Type: Trojan Horse


Run LiveUpdate to make sure that you have the most recent virus definitions.

  1. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
  2. Run a full system scan.
  3. Delete all files that are detected as W32.Nosys.


Writeup By: Gor Nazaryan