O97M.Cybernet.Gen

O97M.Cybernet.Gen is a polymorphic macro virus that infects Microsoft Word and Excel files. It also has a mass-mailing payload similar to W97M.Melissa.A. On August 17 or December 25, a malicious payload is triggered. Due to a bug in the code, under some circumstances this virus may attach uninfected files to the email messages it sends. NOTE: The detection for this virus is a generic detection. It is possible that in some variants, some functionality, such as the trigger dates for the payload, will be changed or removed.

Virus definitions dated July 5, 2001, or earlier detect this virus as O97M.CyberNet.A

Also Known As:	CyberNet, W97M/Pri, O97M.CyberNet.A
Type:	Macro, Virus

Virus Definitions (Intelligent Updater) May 25, 2000

Wild Number of infections: 0 - 49 Number of sites: 0 - 2 Geographical distribution: Low Threat containment: Easy Removal: Easy

Threat Metrics Wild: Low Damage: Medium Distribution: Medium

Damage

• Payload Trigger: · August 17 or December 25
• Payload: Replaces the Autoexec.bat file with one that contains the command to format the C: drive
  • Large scale e-mailing: Uses Microsoft Outlook to send itself to the first 50 email addresses in you address book.
  • Deletes files: It may or may not, depending on the variant, delete all *.XL? files from the Excel startup folder and *.DO? files from the Word StartUp folder.
  • Modifies files: Autoexec.bat, Config.sys, and Office/Excel 97/2000 setting
  • Degrades performance: May clog email server
  • Causes system instability: The payload replaces Config.sys. so the system may no longer boot correctly

Distribution

• Subject of email: You've GOT Mail !!! or Message From [UserName]
• Size of attachment: One MS Word document or one MS Excel spreadsheet

O97M.Cybernet.Gen is a polymorphic macro virus that infects Microsoft Word and Excel files.

In an infected Microsoft Word document, it does the following:

• It disables the Word 97 macro warning or sets the Word 2000 security setting to low.
• It mass-emails the infected document if it has not already done so on that computer.
• It infects the Microsoft Word global template, Normal.dot.
• Some variants of this virus may also:
  • Delete all .xl? files in the Microsoft Excel startup folder (the default location is \Program Files\Microsoft Office\Office\Xlstart)
  • Drop the read-only file, CyberNet.xls, into the Excel startup folder

• It disables the Excel 97 macro warning or sets the Excel 2000 security setting to low.
• It mass-emails the infected worksheet if it has not already done so on that computer.
• It drops the read-only file CyberNet.xls into the Microsoft Excel startup folder. (The default location is \Program Files\Microsoft Office\Office\Xlstart.)
• It deletes the global template Normal.dot. (The default location is \Program Files\Microsoft Office\Template\Normal.dot.)
• It deletes all .do? files from Microsoft Word startup folder. (The default location is \Program Files\Microsoft Office\Office\StartUp.)
• It drops an infected Microsoft Word Normal.dot file.
  
  NOTE: Not all variants of this virus infect Microsoft Excel.

• You've GOT Mail !!!
• Message From [UserName]

• Please, saved the document after you read and don't show to anyone else. The document is also VIRUS FREE...so DISREGARD the virus protection warning !!!
• This document is very Important and you've GOT to read this!!!

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.

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, making sure that NAV is set to scan all files.
3. If any files are detected as infected by O97M.CyberNet.Gen, click Repair.
4. If Normal.dot has been modified or replaced by the virus, locate and delete it to restore the Microsoft Word default settings.
5. If the virus has modified or replaced the Autoexec.bat and Config.sys files, either remove the text added by the virus or replace the files from a clean backup.

Write-up by: Raul Elnitiarta