W97M.Celebrate.A

SUMMARY

W97M.Celebrate.A infects Normal.dot and all active documents. The macro virus disables access to the macro menu.

The virus also turns off virus protection in order to remain undetected.

On the 11th of any month, the payload is executed. See the technical description for payload details.

Protection

• Virus Definitions (Intelligent Updater) October 10, 2000

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
• Payload Trigger: If the date is the 11th of any month
• Modifies Files: C:Autoexec.bat is modified to display messages in Spanish on next startup

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

W97M.Celebrate.A conceals its presence by turning off the VirusProtection option, the ShowVisualBasicEditor option, and by deleting the Macro selection in the Tools menu.

The virus is activated on AutoOpen, AutoClose, New Document, and Document Open. On AutoClose, C:WindowsCommandQbasic.exe is copied to A:~Wd01106.doc.

The virus then attempts to infect the Normal template and all active documents. The virus checks to see if Qbasic.exe is on the infected machine. If the file does not exist, the virus attempts to create it by copying A:~Wd01106.doc to C:WindowsCommandQbasic.exe.

Finally, the virus checks the date. If it is the 11th of the month, the payload is executed.

The payload consists of the following actions:
· Copy C:Autoexec.bat to C:Csp_c_au.bat
· Modify C:Autoexec.bat so that the next time the infected computer starts, some messages are displayed in Spanish.

Some parts of the payload will not work properly if Qbasic.exe is not on the infected computer.

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

Use Norton AntiVirus to repair the infected document