W32.Shiba.Worm

SUMMARY

W32.Shiba.Worm is a mass-mailing worm that sends itself to email addresses that it finds found in files that have the .?bx extension. The email has the following characteristics:

Subject: Hello,Shibatsu.
Message:
Japanese character of the mail text is not displayed correctly.

Then, Japanese details are sent as an attached file.

Read it.
Attachment: Letter.doc.pif

Protection

• Virus Definitions (LiveUpdate™ Weekly) June 5, 2002
• Virus Definitions (Intelligent Updater) June 5, 2002

TECHNICAL DETAILS

When it is run, W32.Shiba.Worm does the following:

First, it copies itself as the following files:

• C:Letter.doc.pif
• C:My DocumentsLetter.doc.pif
• C:WindowsAll Users++¦- -¦¡¦¦¯¦+¦+-++¦-¦»¦¯Start.doc.pif
• C:Windows+¦++-»¦¯âGâNâXâvâìü[âë.pif
• C:Windowsé+é¦éó.scr

Then the worm searches the C:Windows folder and its subfolders for files that have the a .?bx extension.

NOTE: The ? functions as a "wild card." The worm finds all files in the search path where the last two letters of the extension are "bx." For example, it will find Outlook Express .dbx files.

The worm parses these files and extracts email addresses from them. It selects addresses which end in .com, .net, or .jp and which do not start with a digit or contain the string "mag2". These addresses are kept for later use in the mass-mailing routine.

Next the worm searches for .doc and .xls files in all folders on all drives in the computer. If it finds such a file, it attempts to delete it and create a copy of itself in the same location using the double extension .doc.pif or .xls.pif.

If the finds any target email addresses using the procedure previously described, or under special system conditions that the author of the worm designed for debugging purposes, the worm then mails itself. The email message has the following characteristics:

Subject: Hello,Shibatsu.
Message:
Japanese character of the mail text is not displayed correctly.

Then, Japanese details are sent as an attached file.

Read it.
Attachment: Letter.doc.pif

After the worm sends itself, it very quickly uses Notepad to open and close a file that contains a list of the email addresses that it collected.

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

To remove this worm, update the virus definitions, run a full system scan, and delete all files that are detected as W32.Shiba.Worm. For details on how to do this, read the following instructions.

To scan with Norton AntiVirus and delete the infected files:

1. Obtain the most recent virus definitions. There are two ways to do this:
   • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time 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 have undergone full quality assurance testing by Symantec Security Response. They 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.
     
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files.
   • NAV Consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • NAV Enterprise products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
3. Run a full system scan.
4. Delete all files that NAV detected as W32.Shiba.Worm. Replace from a clean backup all files that the worm deleted.