W32.Chiton.gen

The author of this family named the viruses:

• W32.Shrug
• W32.OU812
• W32.Chthon
• W32.EfishNC
• W32.Gemini
• W32.Junkmail

W32.Shrug
W32.Shrug is a direct-action infector of all Windows Portable Executable (PE) files, including .dll's. It infects files that are in the same folder as the virus and in all subfolders. It is the first known virus to use the Thread Local Storage structures that exist in Windows NT/2000/XP to execute the viral code.

W32.OU812
W32.OU812 is a direct-action infector of all Windows Portable Executable applications. It infects files that are in the same folder as the virus and in all subfolders. It is the first known virus to use the language .dll support in Microsoft Visual Basic files to execute the viral code.

W32.Chthon
W32.Chthon is a direct-action infector of all Windows Portable Executable files, including .dll's. It infects files that are in the \Program Files folder and in all subfolders. It is the first known virus to execute as a native application in Windows NT/2000/XP.

W32.EfishNC
W32.EfishNC is a memory-resident infector of all Windows Portable Executable applications. It infects files in all folders on all local and mapped network drives. It also infects files in folders on network shares and IP addresses that are shared with write access. It uses entry-point obscuring (EPO) and an encryption method that is both very simple to implement and very hard to decrypt without the key.

W32.Gemini
W32.Gemini is a memory-resident infector of all Windows Portable Executable applications in all folders on all local and mapped network drives. It is the first known virus for Windows that, to prevent termination of the viral process, maintains two instances of itself executing simultaneously.

W32.Junkmail
W32.Junkmail is a memory-resident infector of all Windows Portable Executable applications in all folders on all local and mapped network drives. It also infects files in folders on network shares and IP addresses that are shared with write access, and can replicate using email. The attachment will be in one of three completely different file formats. It is the first known virus to use polymorphic SMTP headers to hide the presence of the email attachment.

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.

Summary