W97M.Toy.A

SUMMARY

The W97M.Toy.A macro virus infects the Microsoft Word Normal.dot template and uses that template to spread. It also uses mIRC to send itself to other users. It will spread using mIRC only if it finds the Mirc32.exe file on drive C.

Protection

• Virus Definitions (Intelligent Updater) January 24, 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: Low
• Modifies Files: Mirc.ini

Distribution

• Distribution Level: Low
• Name of Attachment: Toy.doc, Game.doc, or Fable.doc
• Target of Infection: *.doc, *.dot files

TECHNICAL DETAILS

This virus infects Microsoft Word documents and templates. When the infected document is opened or closed, the virus will create the C:Toy.vxd file, which contains the virus code. Then the virus will randomly choose one of the following names:

• Toy.doc
• Game.doc
• Fable.doc

and copy itself using one of these file names to the Windows folder.

The virus creates the Default.vxd file in the Windows folder. Default.vxd contains the script to send itself to mIRC users. The virus also adds a line in the Mirc.ini file to point to C:WindowsDefault.vxd.

If mIRC is installed, the virus will use it to send Toy.doc, Game.doc, or Fable.doc to other mIRC users.

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 virus:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and then run a full system scan, making sure that NAV is set to scan all files.
3. If any files are found to be as infected by W97M.Toy.A, click Repair.
4. Click Start, point to Find, and click Files or Folders.
5. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
6. In the Named box, type--or copy and paste--the following three file names:
   
   toy.sys toy.vxd default.vxd
   
7. Click Find Now. Windows will find the files and display them in the lower pane of the Find window.
8. Delete each of the resultant files.
9. Click New Search.
10. In the Named box, type--or copy and paste--the following file name:
    
    mirc.ini
    
11. Click Find Now. Windows will find the file and display in the lower pane of the Find window.
12. Do one of the following:
    • If mirc.ini is not found, you are finished. Close the "Find: All Files" window and restart the computer.
    • If mirc.ini is found, go on to the next step.
13. Double-click the Mirc.ini file. It will open in Notepad.
14. Delete the line in the file that refers to WindowsDefault.vxd.
15. Save your changes, and close Notepad.
16. Close the "Find: All Files" window and then restart the computer.