W32.White.Worm

SUMMARY

W32.White.Worm is an email worm originally discovered in Korea. (A 15 year-old Korean student is the suspected writer of this worm.) When executed, the worm harvests email addresses from your Microsoft Outlook Express inbox and sends messages to these addresses with itself as an attachment.

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

W32.White.Worm is written in Visual Basic 6.0 and requires the files msvmvb60.dll, Mswinsck.ocx, and Msmap32.ocx, and may require additional Visual Basic language .dlls. Without these supporting files, the worm will not execute.
The first time the worm is executed, it pretends to encounter an error when unpacking itself.





Secretly, the worm has copied itself to the ..WindowsSystem directory as Rundll64.exe and adds the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunNHKR

This way, it executes each time you start Windows. The worm is not loaded as a hidden process and can be seen in the Windows Task List.

The worm continually goes through messages in the Microsoft Outlook Express inbox, looking for new email addresses. Email messages are composed and sent to these email addresses with the subject:

Happy to WHITE(FILEz)

the message body:

Happy for ever..to run FILE*^*

and a file attachment named Yourlife.exe as displayed below.



Payload Description:
On the 31st of any month, the virus displays this message:



and overwrites the C:Autoexec.bat file with commands to format drive C.

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

1. Remove the registry key
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunNHKR
   
2. End Task on the Rundll64 process in the Windows Task List and delete any files detected as infected.