Threat Explorer

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25 May 2000
13 February 2007
Also Known As:
CyberNet, W97M/Pri, O97M.CyberNet.A

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

Antivirus Protection Dates

  • Initial Rapid Release version 25 May 2000
  • Latest Rapid Release version 08 November 2017 revision 034
  • Initial Daily Certified version 25 May 2000
  • Latest Daily Certified version 08 November 2017 revision 040
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

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,
  • 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
In an infected Microsoft Excel worksheet, the virus does the following:
  • 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 (The default location is \Program Files\Microsoft Office\Template\
  • 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 file.

    NOTE: Not all variants of this virus infect Microsoft Excel.

The mass-mailing payload is similar to that of W97M.Melissa.A. If it has not already done so, it emails the infected document or worksheet to the first 50 addresses in every address list.

The subject line may vary slightly depending on which variant it is. Those seen so far are:
  • You've GOT Mail !!!
  • Message From [UserName]

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

On December 25, a malicious payload is triggered. (Some variants also execute this payload on August 17.) The virus adds randomly shaped objects to the active document or worksheet. Next, it modifies the Autoexec.bat and Config.sys files. The Autoexec.bat file is replaced with one that contains commands to format drive C.

The virus then displays the message:

Assalamualaikum Li Kulli Muslim...Moslem Power Never End...
Nothing Can Stop << CyberNET >> Virus. Your System Has Already Infected !!!
Now...I Am Outta Here...

There is an OK button; clicking OK will cause Windows to shut down.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Run LiveUpdate to make sure that you have the most recent virus definitions.
  1. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  2. If any files are detected as infected by O97M.CyberNet.Gen, click Repair.
  3. If has been modified or replaced by the virus, locate and delete it to restore the Microsoft Word default settings.
  4. 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.

Writeup By: Raul Elnitiarta