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16 May 2001
13 February 2007
Also Known As:

VBS.Nightflight@mm is a polymorphic mass mailing worm written in the Visual Basic Scripting (VBS) language. The worm can email itself to all contacts in the Microsoft Outlook Address Book. It can also spread by network drives and it contains functionality such as changing the desktop wallpaper, spreading by mIRC, changing the Windows user information, and lowering security settings on the computer.

NOTE: Definitions dated May 16th or earlier will detect this as Bloodhound.VBS.Worm.

Antivirus Protection Dates

  • Initial Rapid Release version 16 May 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 16 May 2001
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When executed,VBS.Nightflight@mm does the following:
  1. It immediately adds itself as a value to the registry key


    The value that the worm adds will have a polymorphic name, but it will always be seven characters with the first character in uppercase and the rest in lowercase. The Value Data of the entry will include the path to the \Windows folder followed by \help.txt.vbs%. This will occur every time that the worm is executed. Therefore, there may be many values in the \Run key that start the worm. Here is an example:

  2. Next, the worm checks for the existence of the key HKEY_CURRENT_USER\Software\Nightflight\send.
    • If the key exists and has a Value Data of 1, the worm will go into an infinite loop. The purpose of this loop is to make sure that it does not get deleted from the system. If the worm is deleted, it will recreate itself.
    • If the key does not exist or does not have the value 1, the worm will perform all of its malicious actions.
  3. The worm starts by changing its own comments. This appears to be an attempt to make detection of the worm more difficult. However, the routine the worm uses is very simple. It just inserts random comments in random places. The worm does not remove the old comments, so every time this function is executed, it will increase the worm in size. The worm will also make an attempt to lower the security settings on the computer.

    All variants of this worm are detected by the heuristics detection in Norton AntiVirus even with definitions dated prior to May 16th.
  4. The worm will then try to send itself to all contacts in the Microsoft Outlook Address Book. This worm contains a check, so it will not work with any client other than Microsoft Outlook.
  5. VBS.Nightflight@mm contains the functionality to spread using mIRC, a popular IRC client for Microsoft Windows. The worm will attempt to locate the Mirc.ini file, both locally and over mapped network drives. If the file is found, it will insert the Script.ini into the same folder as the Mirc.ini file. Once this occurs, the worm will be sent to other users over the IRC network as they join the network that you are using. It will also generate messages to other mIRC users when certain events occur; these messages will appear to have been sent by you.
  6. Next the worm will attempt to copy itself once into all folders on all mapped network drives that it can find.
  7. It will also attempt to change the desktop wallpaper. If the day is Friday, it will change a registry key so that all icons disappear from the Windows desktop, and the desktop becomes inaccessible. The worm will make add itself to the Windows registry so that when right-clicking anything, the option "Start the nightflight" will appear. If this option is selected, the worm will be executed.
  8. VBS.Nightflight@mm will change the registration information in the Windows registry, so the registration name will appear as Nightflight and the company name will be Carpe Noctem. Carpe Noctem appears to be a German band that plays black metal music; the first submission of this worm to SARC arrived from Germany.
  9. Next, if the day of the week is Saturday, the worm will check if Microsoft Agent version 2 is installed on the system. Specifically, the worm is looking for the presence of the Microsoft agent Merlin. If Merlin is found on the system, the worm will show him in a small window and have him say: "The Nightflight is still out there".
  10. Finally, the worm will enter the infinite loop that constantly checks so that the worm does not get deleted.


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.

To remove this worm, delete files detected as VBS.Nightflight@mm, and undo the changes it made to the registry.

To remove the worm:
  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. Delete any files detected as VBS.Nightflight@mm.

To edit the registry:

CAUTION : We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the following key:

  4. In the Name column of the right pane, look for and delete any values that have seven characters, with the first character in uppercase and the rest lowercase. The Value Data of the entry will include the path to the \Windows folder followed by \help.txt.vbs%. For example:

  5. Click Registry, and then click Exit

Writeup By: Neal Hindocha