W32.Shiba.Worm

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

First, it copies itself as the following files:

• C:\Letter.doc.pif
• C:\My Documents\Letter.doc.pif
• C:\Windows\All Users\++¦- -¦¡¦\¦¯¦+¦+-\++¦-¦»¦¯\Start.doc.pif
• C:\Windows\+¦++-»¦¯\âGâNâXâvâìü[âë.pif
• C:\Windows\é+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":

• 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