Trojan.VBS.Never

SUMMARY

This is a Trojan horse coded in Visual Basic Script (VBS). It overwrites the C:Autoexec.bat file with instructions to delete files the next time that you start Windows. This does not affect Windows NT/2000 systems.

Protection

• Virus Definitions (Intelligent Updater) August 9, 2001

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: High
• Payload Trigger: Boot-time
• Deletes Files: Yes
• Modifies Files: Overwrites c:autoexec.bat
• Causes System Instability: Yes

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When executed, the script accesses the local file system and writes a new file (or overwrites if it exists) as C:Autoexec.bat

The new or overwritten file contains instructions to delete:
C:WindowsSystem*.*
C:Windows*.*
C:*.*

The file also contains output strings, which will be displayed the next time that you start Windows:

"Was meinst du ist real?"
"Press any key when ready..."

If you then press a key, it displays:

"das, dass du dich in sicherheit wagst?"
"Press any key when ready..."

If you then press a key, it displays:

"nein! nichts ist sicher! (c) DaS_cHaOs by real!"

NOTE: Depending on the speed of the computer on Windows 95/98/Me systems, the Windows logo bitmap screen may prevent you from seeing any of these messages, and the boot process may appear to hang. In this case, if you pressed the Esc key, you would see this message.

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

NOTE: If the instructions in the Autoexec.bat file have already executed, you will first have to reinstall Windows and all programs that were installed to the C drive.

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV) and run a full system scan. Be sure that NAV is configured to scan all files.
3. Delete all files that are detected as Trojan.VBS.Never.
4. Restore the Autoexec.bat from a clean backup.