JS/VBS.LostSoul.Worm

JS/VBS.LostSoul.Worm spreads via Microsoft Outlook and shared network drives. It arrives as an attachment named Wobbler.txt.vbe or Wobbler.txt.jse. When either file is executed, it creates a file in the default temporary folder. The file is given a random name, but always has a .wsc extension. The temp file contains malicious code.

When the temp file is created, the worm displays a text file containing the Wobbler Hoax. As the user reads the text file, the worm executes the malicious code.
The worm first checks to see how many addresses are in the Microsoft Outlook address book. If more than 100 email addresses are found, the worm randomly selects 100 of them. It then emails itself to these 100 addresses. If less than 100 addresses are found, it emails itself to everyone in the address book.

When it has finished emailing itself, the worm randomly generates a number between 0 and 5. If the number is 0, the worm sends an email containing a short poem in Spanish. The subject line of the email is Alma.
The poem is as follows:

"No alucines que te amo, cuando en realidad es solo, mi corazon quien lo hace. Porque como ya sabras, mi corazon no manda en mi vida, si asi lo hiciera, mi alma estaria perdida."

In English:
"Don't think I love you, when in reality, it's only my heart who does. Because as you probably know, my heart doesn't manage my life. If it did, my soul would be lost."

The worm also spreads via shared drives. It checks the network for shared drives. If any are found, the worm attempts to copy itself to the root directories of the drives.

The worm deletes all files that it creates, except for Wobbler.txt, which contains the Wobbler Hoax.

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