W32.BatmanTroj

SUMMARY

This is a destructive Trojan horse. There is no specific file name that is used to distribute it.

Protection

• Virus Definitions (Intelligent Updater) February 6, 2001

Threat Assessment

Wild

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

Damage

• Damage Level: High
• Payload Trigger: Run the Trojan
• Deletes Files: See Technical Description for the list of the deleted files
• Causes System Instability: Windows will no longer load.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

This Trojan horse deletes files.

• It deletes all files from the root of C:, including Autoexec.bat, Command.com and Config.sys.
• From the C:Windows folder, it deletes:
  • Himem.sys
  • Win.ini
  • System.ini
  • Protocol.ini
• From the C:WindowsSystem folder, it deletes El90x???.sys (This is apparently a backup file.)

Because this effectively deletes the operating system, Windows will not load.

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

If Norton AntiVirus detects a file as infected with W32.BatmanTroj, delete it. If the Trojan has already run, in most cases you will have to reinstall Windows.