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Discovered: February 12, 2003
Updated: February 13, 2007 12:46:58 PM
Type: Macro
Systems Affected: Windows

X97M.Cian.C@mm is a mass-mailing macro virus that infects Microsoft Excel spreadsheets. This macro virus has a VBS script inside itself that it inserts and executes on the system. This VBS script is detected as VBS.Cian.C .

Antivirus Protection Dates

  • Initial Rapid Release version February 13, 2003
  • Latest Rapid Release version February 13, 2003
  • Initial Daily Certified version February 13, 2003
  • Latest Daily Certified version February 13, 2003
  • Initial Weekly Certified release date February 19, 2003

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Atli Gudmundsson

Discovered: February 12, 2003
Updated: February 13, 2007 12:46:58 PM
Type: Macro
Systems Affected: Windows

When a Microsoft Excel spreadsheet infected with X97M.Cian.C@mm is opened, the virus does the following:


  1. Attempts to hide its malicious actions by disabling several toolbars and lowering the Microsoft Excel Macro virus protection security setting. The disabled toolbars are:
    • Tools>Macro
    • Tools>Macro>Security
    • Tools>Macro>Macros
    • Tools>Macro>Customize
    • View>Toolsbars
    • Format>Object
  2. Exports its viral code as %System%\Evade.gif.

    NOTE: %System% is a variable. The virus locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
  3. Infects the Microsoft Excel Personal template, Personal.xls. This causes the virus to execute when you start Microsoft Excel. Once this happens, when you open or close a document, the virus will infect the template by importing its viral code from the export file.

After the infection routine has been executed, the virus runs its email routine, and does the following:
  1. Creates the registry key:


    When an email is sent, the virus records the address in this key, so that it sends email to each contact or group only once.
  2. Sends the following email to all the contacts in the Windows Address Book:
    • Subject: The subject is chosen at random from the following:
      • Here is that file
      • Important file
      • The file
      • Excel file
      • [Name of infected document]
      • The file you wanted
      • Here is the file
    • Message: The file I am sending you is confidential as well as important; so don't let anyone else have a copy.
    • Attachment: The worm attaches an infected Microsoft Excel spreadsheet to the email message,

VBS File Insertion
Once the virus has sent the email messages, it creates the file, %System%\Winstart.vbs, which contains the VBS.Cian.C worm component.

X97M.Cian.C@mm creates the registry value:

winstart wscript.exe %system%\winstart.vbs %1

in the registry key:


so that the virus runs each time you start Windows.


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.

Writeup By: Atli Gudmundsson

Discovered: February 12, 2003
Updated: February 13, 2007 12:46:58 PM
Type: Macro
Systems Affected: Windows

These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Update the virus definitions.
  2. Run a full system scan and repair all the files detected as X97M.Cian.C@mm.
  3. Delete the value: winstart

    from the registry key:

For specific details on each of these procedures, read the following instructions.

1. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain the virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate), in the "Protection" section, at the top of this writeup.
  • Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater), in the "Protection" section, at the top of this writeup.

    The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

2. Scanning for and repairing the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with X97M.Cian.C@mm, click Repair.

3. Deleting the value from the registry

CAUTION : Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)
  3. Navigate to the key:

  4. In the right pane, delete the value: winstart
  5. Exit the Registry Editor.

Writeup By: Atli Gudmundsson